| Message ID | 20211119084241.14984-1-harshit.m.mogalapalli@oracle.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: sched: sch_netem: Fix a divide error in netem_enqueue during randomized corruption. | expand |
On 11/19/21 12:42 AM, Harshit Mogalapalli wrote: > In netem_enqueue function the value of skb_headlen(skb) can be zero > which leads to a division error during randomized corruption of the packet. > This fix adds a check to skb_headlen(skb) to prevent the division error. > > Crash report: > [ 343.170349] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family > 0 port 6081 - 0 > [ 343.216110] netem: version 1.3 > [ 343.235841] divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI > [ 343.236680] CPU: 3 PID: 4288 Comm: reproducer Not tainted 5.16.0-rc1+ > [ 343.237569] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS 1.11.0-2.el7 04/01/2014 > [ 343.238707] RIP: 0010:netem_enqueue+0x1590/0x33c0 [sch_netem] > [ 343.239499] Code: 89 85 58 ff ff ff e8 5f 5d e9 d3 48 8b b5 48 ff ff > ff 8b 8d 50 ff ff ff 8b 85 58 ff ff ff 48 8b bd 70 ff ff ff 31 d2 2b 4f > 74 <f7> f1 48 b8 00 00 00 00 00 fc ff df 49 01 d5 4c 89 e9 48 c1 e9 03 > [ 343.241883] RSP: 0018:ffff88800bcd7368 EFLAGS: 00010246 > [ 343.242589] RAX: 00000000ba7c0a9c RBX: 0000000000000001 RCX: > 0000000000000000 > [ 343.243542] RDX: 0000000000000000 RSI: ffff88800f8edb10 RDI: > ffff88800f8eda40 > [ 343.244474] RBP: ffff88800bcd7458 R08: 0000000000000000 R09: > ffffffff94fb8445 > [ 343.245403] R10: ffffffff94fb8336 R11: ffffffff94fb8445 R12: > 0000000000000000 > [ 343.246355] R13: ffff88800a5a7000 R14: ffff88800a5b5800 R15: > 0000000000000020 > [ 343.247291] FS: 00007fdde2bd7700(0000) GS:ffff888109780000(0000) > knlGS:0000000000000000 > [ 343.248350] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 343.249120] CR2: 00000000200000c0 CR3: 000000000ef4c000 CR4: > 00000000000006e0 > [ 343.250076] Call Trace: > [ 343.250423] <TASK> > [ 343.250713] ? memcpy+0x4d/0x60 > [ 343.251162] ? netem_init+0xa0/0xa0 [sch_netem] > [ 343.251795] ? __sanitizer_cov_trace_pc+0x21/0x60 > [ 343.252443] netem_enqueue+0xe28/0x33c0 [sch_netem] > [ 343.253102] ? stack_trace_save+0x87/0xb0 > [ 343.253655] ? filter_irq_stacks+0xb0/0xb0 > [ 343.254220] ? netem_init+0xa0/0xa0 [sch_netem] > [ 343.254837] ? __kasan_check_write+0x14/0x20 > [ 343.255418] ? _raw_spin_lock+0x88/0xd6 > [ 343.255953] dev_qdisc_enqueue+0x50/0x180 > [ 343.256508] __dev_queue_xmit+0x1a7e/0x3090 > [ 343.257083] ? netdev_core_pick_tx+0x300/0x300 > [ 343.257690] ? check_kcov_mode+0x10/0x40 > [ 343.258219] ? _raw_spin_unlock_irqrestore+0x29/0x40 > [ 343.258899] ? __kasan_init_slab_obj+0x24/0x30 > [ 343.259529] ? setup_object.isra.71+0x23/0x90 > [ 343.260121] ? new_slab+0x26e/0x4b0 > [ 343.260609] ? kasan_poison+0x3a/0x50 > [ 343.261118] ? kasan_unpoison+0x28/0x50 > [ 343.261637] ? __kasan_slab_alloc+0x71/0x90 > [ 343.262214] ? memcpy+0x4d/0x60 > [ 343.262674] ? write_comp_data+0x2f/0x90 > [ 343.263209] ? __kasan_check_write+0x14/0x20 > [ 343.263802] ? __skb_clone+0x5d6/0x840 > [ 343.264329] ? __sanitizer_cov_trace_pc+0x21/0x60 > [ 343.264958] dev_queue_xmit+0x1c/0x20 > [ 343.265470] netlink_deliver_tap+0x652/0x9c0 > [ 343.266067] netlink_unicast+0x5a0/0x7f0 > [ 343.266608] ? netlink_attachskb+0x860/0x860 > [ 343.267183] ? __sanitizer_cov_trace_pc+0x21/0x60 > [ 343.267820] ? write_comp_data+0x2f/0x90 > [ 343.268367] netlink_sendmsg+0x922/0xe80 > [ 343.268899] ? netlink_unicast+0x7f0/0x7f0 > [ 343.269472] ? __sanitizer_cov_trace_pc+0x21/0x60 > [ 343.270099] ? write_comp_data+0x2f/0x90 > [ 343.270644] ? netlink_unicast+0x7f0/0x7f0 > [ 343.271210] sock_sendmsg+0x155/0x190 > [ 343.271721] ____sys_sendmsg+0x75f/0x8f0 > [ 343.272262] ? kernel_sendmsg+0x60/0x60 > [ 343.272788] ? write_comp_data+0x2f/0x90 > [ 343.273332] ? write_comp_data+0x2f/0x90 > [ 343.273869] ___sys_sendmsg+0x10f/0x190 > [ 343.274405] ? sendmsg_copy_msghdr+0x80/0x80 > [ 343.274984] ? slab_post_alloc_hook+0x70/0x230 > [ 343.275597] ? futex_wait_setup+0x240/0x240 > [ 343.276175] ? security_file_alloc+0x3e/0x170 > [ 343.276779] ? write_comp_data+0x2f/0x90 > [ 343.277313] ? __sanitizer_cov_trace_pc+0x21/0x60 > [ 343.277969] ? write_comp_data+0x2f/0x90 > [ 343.278515] ? __fget_files+0x1ad/0x260 > [ 343.279048] ? __sanitizer_cov_trace_pc+0x21/0x60 > [ 343.279685] ? write_comp_data+0x2f/0x90 > [ 343.280234] ? __sanitizer_cov_trace_pc+0x21/0x60 > [ 343.280874] ? sockfd_lookup_light+0xd1/0x190 > [ 343.281481] __sys_sendmsg+0x118/0x200 > [ 343.281998] ? __sys_sendmsg_sock+0x40/0x40 > [ 343.282578] ? alloc_fd+0x229/0x5e0 > [ 343.283070] ? write_comp_data+0x2f/0x90 > [ 343.283610] ? write_comp_data+0x2f/0x90 > [ 343.284135] ? __sanitizer_cov_trace_pc+0x21/0x60 > [ 343.284776] ? ktime_get_coarse_real_ts64+0xb8/0xf0 > [ 343.285450] __x64_sys_sendmsg+0x7d/0xc0 > [ 343.285981] ? syscall_enter_from_user_mode+0x4d/0x70 > [ 343.286664] do_syscall_64+0x3a/0x80 > [ 343.287158] entry_SYSCALL_64_after_hwframe+0x44/0xae > [ 343.287850] RIP: 0033:0x7fdde24cf289 > [ 343.288344] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 > 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f > 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b7 db 2c 00 f7 d8 64 89 01 48 > [ 343.290729] RSP: 002b:00007fdde2bd6d98 EFLAGS: 00000246 ORIG_RAX: > 000000000000002e > [ 343.291730] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: > 00007fdde24cf289 > [ 343.292673] RDX: 0000000000000000 RSI: 00000000200000c0 RDI: > 0000000000000004 > [ 343.293618] RBP: 00007fdde2bd6e20 R08: 0000000100000001 R09: > 0000000000000000 > [ 343.294557] R10: 0000000100000001 R11: 0000000000000246 R12: > 0000000000000000 > [ 343.295493] R13: 0000000000021000 R14: 0000000000000000 R15: > 00007fdde2bd7700 > [ 343.296432] </TASK> > [ 343.296735] Modules linked in: sch_netem ip6_vti ip_vti ip_gre ipip > sit ip_tunnel geneve macsec macvtap tap ipvlan macvlan 8021q garp mrp > hsr wireguard libchacha20poly1305 chacha_x86_64 poly1305_x86_64 > ip6_udp_tunnel udp_tunnel libblake2s blake2s_x86_64 libblake2s_generic > curve25519_x86_64 libcurve25519_generic libchacha xfrm_interface > xfrm6_tunnel tunnel4 veth netdevsim psample batman_adv nlmon dummy team > bonding tls vcan ip6_gre ip6_tunnel tunnel6 gre tun ip6t_rpfilter > ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set > ebtable_nat ebtable_broute ip6table_nat ip6table_mangle > ip6table_security ip6table_raw iptable_nat nf_nat nf_conntrack > nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle iptable_security > iptable_raw ebtable_filter ebtables rfkill ip6table_filter ip6_tables > iptable_filter ppdev bochs drm_vram_helper drm_ttm_helper ttm > drm_kms_helper cec parport_pc drm joydev floppy parport sg syscopyarea > sysfillrect sysimgblt i2c_piix4 qemu_fw_cfg fb_sys_fops pcspkr > [ 343.297459] ip_tables xfs virtio_net net_failover failover sd_mod > sr_mod cdrom t10_pi ata_generic pata_acpi ata_piix libata virtio_pci > virtio_pci_legacy_dev serio_raw virtio_pci_modern_dev dm_mirror > dm_region_hash dm_log dm_mod > [ 343.311074] Dumping ftrace buffer: > [ 343.311532] (ftrace buffer empty) > [ 343.312040] ---[ end trace a2e3db5a6ae05099 ]--- > [ 343.312691] RIP: 0010:netem_enqueue+0x1590/0x33c0 [sch_netem] > [ 343.313481] Code: 89 85 58 ff ff ff e8 5f 5d e9 d3 48 8b b5 48 ff ff > ff 8b 8d 50 ff ff ff 8b 85 58 ff ff ff 48 8b bd 70 ff ff ff 31 d2 2b 4f > 74 <f7> f1 48 b8 00 00 00 00 00 fc ff df 49 01 d5 4c 89 e9 48 c1 e9 03 > [ 343.315893] RSP: 0018:ffff88800bcd7368 EFLAGS: 00010246 > [ 343.316622] RAX: 00000000ba7c0a9c RBX: 0000000000000001 RCX: > 0000000000000000 > [ 343.317585] RDX: 0000000000000000 RSI: ffff88800f8edb10 RDI: > ffff88800f8eda40 > [ 343.318549] RBP: ffff88800bcd7458 R08: 0000000000000000 R09: > ffffffff94fb8445 > [ 343.319503] R10: ffffffff94fb8336 R11: ffffffff94fb8445 R12: > 0000000000000000 > [ 343.320455] R13: ffff88800a5a7000 R14: ffff88800a5b5800 R15: > 0000000000000020 > [ 343.321414] FS: 00007fdde2bd7700(0000) GS:ffff888109780000(0000) > knlGS:0000000000000000 > [ 343.322489] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 343.323283] CR2: 00000000200000c0 CR3: 000000000ef4c000 CR4: > 00000000000006e0 > [ 343.324264] Kernel panic - not syncing: Fatal exception in interrupt > [ 343.333717] Dumping ftrace buffer: > [ 343.334175] (ftrace buffer empty) > [ 343.334653] Kernel Offset: 0x13600000 from 0xffffffff81000000 > (relocation range: 0xffffffff80000000-0xffffffffbfffffff) > [ 343.336027] Rebooting in 86400 seconds.. > > Reported-by: syzkaller <syzkaller@googlegroups.com> > Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> > --- > net/sched/sch_netem.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c > index ecbb10db1111..e1e1a00fedda 100644 > --- a/net/sched/sch_netem.c > +++ b/net/sched/sch_netem.c > @@ -513,8 +513,14 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch, > goto finish_segs; > } > > - skb->data[prandom_u32() % skb_headlen(skb)] ^= > - 1<<(prandom_u32() % 8); > + if (unlikely(!skb_headlen(skb))) { > + qdisc_drop(skb, sch, to_free); > + skb = NULL; > + goto finish_segs; > + } else { > + skb->data[prandom_u32() % skb_headlen(skb)] ^= > + 1<<(prandom_u32() % 8); > + } > } > > if (unlikely(sch->q.qlen >= sch->limit)) { > If we accept the fact that a packet can reach qdisc with nothing in skb->head, then we have other serious issues. Why dropping the packet ? I would rather pull headers here.
On Fri, 19 Nov 2021 07:49:59 -0800 Eric Dumazet <eric.dumazet@gmail.com> wrote: > On 11/19/21 12:42 AM, Harshit Mogalapalli wrote: > > In netem_enqueue function the value of skb_headlen(skb) can be zero > > which leads to a division error during randomized corruption of the packet. > > This fix adds a check to skb_headlen(skb) to prevent the division error. > > > > Crash report: > > [ 343.170349] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family > > 0 port 6081 - 0 > > [ 343.216110] netem: version 1.3 > > [ 343.235841] divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI > > [ 343.236680] CPU: 3 PID: 4288 Comm: reproducer Not tainted 5.16.0-rc1+ > > [ 343.237569] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > > BIOS 1.11.0-2.el7 04/01/2014 > > [ 343.238707] RIP: 0010:netem_enqueue+0x1590/0x33c0 [sch_netem] > > [ 343.239499] Code: 89 85 58 ff ff ff e8 5f 5d e9 d3 48 8b b5 48 ff ff > > ff 8b 8d 50 ff ff ff 8b 85 58 ff ff ff 48 8b bd 70 ff ff ff 31 d2 2b 4f > > 74 <f7> f1 48 b8 00 00 00 00 00 fc ff df 49 01 d5 4c 89 e9 48 c1 e9 03 > > [ 343.241883] RSP: 0018:ffff88800bcd7368 EFLAGS: 00010246 > > [ 343.242589] RAX: 00000000ba7c0a9c RBX: 0000000000000001 RCX: > > 0000000000000000 > > [ 343.243542] RDX: 0000000000000000 RSI: ffff88800f8edb10 RDI: > > ffff88800f8eda40 > > [ 343.244474] RBP: ffff88800bcd7458 R08: 0000000000000000 R09: > > ffffffff94fb8445 > > [ 343.245403] R10: ffffffff94fb8336 R11: ffffffff94fb8445 R12: > > 0000000000000000 > > [ 343.246355] R13: ffff88800a5a7000 R14: ffff88800a5b5800 R15: > > 0000000000000020 > > [ 343.247291] FS: 00007fdde2bd7700(0000) GS:ffff888109780000(0000) > > knlGS:0000000000000000 > > [ 343.248350] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 343.249120] CR2: 00000000200000c0 CR3: 000000000ef4c000 CR4: > > 00000000000006e0 > > [ 343.250076] Call Trace: > > [ 343.250423] <TASK> > > [ 343.250713] ? memcpy+0x4d/0x60 > > [ 343.251162] ? netem_init+0xa0/0xa0 [sch_netem] > > [ 343.251795] ? __sanitizer_cov_trace_pc+0x21/0x60 > > [ 343.252443] netem_enqueue+0xe28/0x33c0 [sch_netem] > > [ 343.253102] ? stack_trace_save+0x87/0xb0 > > [ 343.253655] ? filter_irq_stacks+0xb0/0xb0 > > [ 343.254220] ? netem_init+0xa0/0xa0 [sch_netem] > > [ 343.254837] ? __kasan_check_write+0x14/0x20 > > [ 343.255418] ? _raw_spin_lock+0x88/0xd6 > > [ 343.255953] dev_qdisc_enqueue+0x50/0x180 > > [ 343.256508] __dev_queue_xmit+0x1a7e/0x3090 > > [ 343.257083] ? netdev_core_pick_tx+0x300/0x300 > > [ 343.257690] ? check_kcov_mode+0x10/0x40 > > [ 343.258219] ? _raw_spin_unlock_irqrestore+0x29/0x40 > > [ 343.258899] ? __kasan_init_slab_obj+0x24/0x30 > > [ 343.259529] ? setup_object.isra.71+0x23/0x90 > > [ 343.260121] ? new_slab+0x26e/0x4b0 > > [ 343.260609] ? kasan_poison+0x3a/0x50 > > [ 343.261118] ? kasan_unpoison+0x28/0x50 > > [ 343.261637] ? __kasan_slab_alloc+0x71/0x90 > > [ 343.262214] ? memcpy+0x4d/0x60 > > [ 343.262674] ? write_comp_data+0x2f/0x90 > > [ 343.263209] ? __kasan_check_write+0x14/0x20 > > [ 343.263802] ? __skb_clone+0x5d6/0x840 > > [ 343.264329] ? __sanitizer_cov_trace_pc+0x21/0x60 > > [ 343.264958] dev_queue_xmit+0x1c/0x20 > > [ 343.265470] netlink_deliver_tap+0x652/0x9c0 > > [ 343.266067] netlink_unicast+0x5a0/0x7f0 > > [ 343.266608] ? netlink_attachskb+0x860/0x860 > > [ 343.267183] ? __sanitizer_cov_trace_pc+0x21/0x60 > > [ 343.267820] ? write_comp_data+0x2f/0x90 > > [ 343.268367] netlink_sendmsg+0x922/0xe80 > > [ 343.268899] ? netlink_unicast+0x7f0/0x7f0 > > [ 343.269472] ? __sanitizer_cov_trace_pc+0x21/0x60 > > [ 343.270099] ? write_comp_data+0x2f/0x90 > > [ 343.270644] ? netlink_unicast+0x7f0/0x7f0 > > [ 343.271210] sock_sendmsg+0x155/0x190 > > [ 343.271721] ____sys_sendmsg+0x75f/0x8f0 > > [ 343.272262] ? kernel_sendmsg+0x60/0x60 > > [ 343.272788] ? write_comp_data+0x2f/0x90 > > [ 343.273332] ? write_comp_data+0x2f/0x90 > > [ 343.273869] ___sys_sendmsg+0x10f/0x190 > > [ 343.274405] ? sendmsg_copy_msghdr+0x80/0x80 > > [ 343.274984] ? slab_post_alloc_hook+0x70/0x230 > > [ 343.275597] ? futex_wait_setup+0x240/0x240 > > [ 343.276175] ? security_file_alloc+0x3e/0x170 > > [ 343.276779] ? write_comp_data+0x2f/0x90 > > [ 343.277313] ? __sanitizer_cov_trace_pc+0x21/0x60 > > [ 343.277969] ? write_comp_data+0x2f/0x90 > > [ 343.278515] ? __fget_files+0x1ad/0x260 > > [ 343.279048] ? __sanitizer_cov_trace_pc+0x21/0x60 > > [ 343.279685] ? write_comp_data+0x2f/0x90 > > [ 343.280234] ? __sanitizer_cov_trace_pc+0x21/0x60 > > [ 343.280874] ? sockfd_lookup_light+0xd1/0x190 > > [ 343.281481] __sys_sendmsg+0x118/0x200 > > [ 343.281998] ? __sys_sendmsg_sock+0x40/0x40 > > [ 343.282578] ? alloc_fd+0x229/0x5e0 > > [ 343.283070] ? write_comp_data+0x2f/0x90 > > [ 343.283610] ? write_comp_data+0x2f/0x90 > > [ 343.284135] ? __sanitizer_cov_trace_pc+0x21/0x60 > > [ 343.284776] ? ktime_get_coarse_real_ts64+0xb8/0xf0 > > [ 343.285450] __x64_sys_sendmsg+0x7d/0xc0 > > [ 343.285981] ? syscall_enter_from_user_mode+0x4d/0x70 > > [ 343.286664] do_syscall_64+0x3a/0x80 > > [ 343.287158] entry_SYSCALL_64_after_hwframe+0x44/0xae > > [ 343.287850] RIP: 0033:0x7fdde24cf289 > > [ 343.288344] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 > > 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f > > 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b7 db 2c 00 f7 d8 64 89 01 48 > > [ 343.290729] RSP: 002b:00007fdde2bd6d98 EFLAGS: 00000246 ORIG_RAX: > > 000000000000002e > > [ 343.291730] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: > > 00007fdde24cf289 > > [ 343.292673] RDX: 0000000000000000 RSI: 00000000200000c0 RDI: > > 0000000000000004 > > [ 343.293618] RBP: 00007fdde2bd6e20 R08: 0000000100000001 R09: > > 0000000000000000 > > [ 343.294557] R10: 0000000100000001 R11: 0000000000000246 R12: > > 0000000000000000 > > [ 343.295493] R13: 0000000000021000 R14: 0000000000000000 R15: > > 00007fdde2bd7700 > > [ 343.296432] </TASK> > > [ 343.296735] Modules linked in: sch_netem ip6_vti ip_vti ip_gre ipip > > sit ip_tunnel geneve macsec macvtap tap ipvlan macvlan 8021q garp mrp > > hsr wireguard libchacha20poly1305 chacha_x86_64 poly1305_x86_64 > > ip6_udp_tunnel udp_tunnel libblake2s blake2s_x86_64 libblake2s_generic > > curve25519_x86_64 libcurve25519_generic libchacha xfrm_interface > > xfrm6_tunnel tunnel4 veth netdevsim psample batman_adv nlmon dummy team > > bonding tls vcan ip6_gre ip6_tunnel tunnel6 gre tun ip6t_rpfilter > > ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set > > ebtable_nat ebtable_broute ip6table_nat ip6table_mangle > > ip6table_security ip6table_raw iptable_nat nf_nat nf_conntrack > > nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle iptable_security > > iptable_raw ebtable_filter ebtables rfkill ip6table_filter ip6_tables > > iptable_filter ppdev bochs drm_vram_helper drm_ttm_helper ttm > > drm_kms_helper cec parport_pc drm joydev floppy parport sg syscopyarea > > sysfillrect sysimgblt i2c_piix4 qemu_fw_cfg fb_sys_fops pcspkr > > [ 343.297459] ip_tables xfs virtio_net net_failover failover sd_mod > > sr_mod cdrom t10_pi ata_generic pata_acpi ata_piix libata virtio_pci > > virtio_pci_legacy_dev serio_raw virtio_pci_modern_dev dm_mirror > > dm_region_hash dm_log dm_mod > > [ 343.311074] Dumping ftrace buffer: > > [ 343.311532] (ftrace buffer empty) > > [ 343.312040] ---[ end trace a2e3db5a6ae05099 ]--- > > [ 343.312691] RIP: 0010:netem_enqueue+0x1590/0x33c0 [sch_netem] > > [ 343.313481] Code: 89 85 58 ff ff ff e8 5f 5d e9 d3 48 8b b5 48 ff ff > > ff 8b 8d 50 ff ff ff 8b 85 58 ff ff ff 48 8b bd 70 ff ff ff 31 d2 2b 4f > > 74 <f7> f1 48 b8 00 00 00 00 00 fc ff df 49 01 d5 4c 89 e9 48 c1 e9 03 > > [ 343.315893] RSP: 0018:ffff88800bcd7368 EFLAGS: 00010246 > > [ 343.316622] RAX: 00000000ba7c0a9c RBX: 0000000000000001 RCX: > > 0000000000000000 > > [ 343.317585] RDX: 0000000000000000 RSI: ffff88800f8edb10 RDI: > > ffff88800f8eda40 > > [ 343.318549] RBP: ffff88800bcd7458 R08: 0000000000000000 R09: > > ffffffff94fb8445 > > [ 343.319503] R10: ffffffff94fb8336 R11: ffffffff94fb8445 R12: > > 0000000000000000 > > [ 343.320455] R13: ffff88800a5a7000 R14: ffff88800a5b5800 R15: > > 0000000000000020 > > [ 343.321414] FS: 00007fdde2bd7700(0000) GS:ffff888109780000(0000) > > knlGS:0000000000000000 > > [ 343.322489] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 343.323283] CR2: 00000000200000c0 CR3: 000000000ef4c000 CR4: > > 00000000000006e0 > > [ 343.324264] Kernel panic - not syncing: Fatal exception in interrupt > > [ 343.333717] Dumping ftrace buffer: > > [ 343.334175] (ftrace buffer empty) > > [ 343.334653] Kernel Offset: 0x13600000 from 0xffffffff81000000 > > (relocation range: 0xffffffff80000000-0xffffffffbfffffff) > > [ 343.336027] Rebooting in 86400 seconds.. > > > > Reported-by: syzkaller <syzkaller@googlegroups.com> > > Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> > > --- > > net/sched/sch_netem.c | 10 ++++++++-- > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c > > index ecbb10db1111..e1e1a00fedda 100644 > > --- a/net/sched/sch_netem.c > > +++ b/net/sched/sch_netem.c > > @@ -513,8 +513,14 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch, > > goto finish_segs; > > } > > > > - skb->data[prandom_u32() % skb_headlen(skb)] ^= > > - 1<<(prandom_u32() % 8); > > + if (unlikely(!skb_headlen(skb))) { > > + qdisc_drop(skb, sch, to_free); > > + skb = NULL; > > + goto finish_segs; > > + } else { > > + skb->data[prandom_u32() % skb_headlen(skb)] ^= > > + 1<<(prandom_u32() % 8); > > + } > > } > > > > if (unlikely(sch->q.qlen >= sch->limit)) { > > > > > If we accept the fact that a packet can reach qdisc with nothing in skb->head, > then we have other serious issues. > > Why dropping the packet ? > > I would rather pull headers here. > Agree with Eric, would be to just linearize befor the corruption step. There is also the issue of checksum offload here.
On Wed, 24 Nov 2021 10:15:12 +0000 Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> wrote: > Hi Stephen and Eric, > > Thanks for the comments. > > Syzkaller reproducer fuzzes in a way that socket buffer length is zero. > So skb_linearize would not help in this case as skb->data_len=0 and skb->len=0 > due to which skb_headlen=0 before corruption. > > I edited my patch which just adds a check on skb_headlen before performing corruption and I > am sending a v2 of the patch. > > Thanks, > Harshit > ________________________________ > From: Stephen Hemminger <stephen@networkplumber.org> > Sent: Friday, November 19, 2021 10:31 PM > To: Eric Dumazet <eric.dumazet@gmail.com> > Cc: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>; Vijayendra Suman <vijayendra.suman@oracle.com>; Ramanan Govindarajan <ramanan.govindarajan@oracle.com>; George Kennedy <george.kennedy@oracle.com>; syzkaller <syzkaller@googlegroups.com>; Jamal Hadi Salim <jhs@mojatatu.com>; Cong Wang <xiyou.wangcong@gmail.com>; Jiri Pirko <jiri@resnulli.us>; David S. Miller <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; netdev@vger.kernel.org <netdev@vger.kernel.org>; linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org> > Subject: [External] : Re: [PATCH] net: sched: sch_netem: Fix a divide error in netem_enqueue during randomized corruption. > > On Fri, 19 Nov 2021 07:49:59 -0800 > Eric Dumazet <eric.dumazet@gmail.com> wrote: > > > On 11/19/21 12:42 AM, Harshit Mogalapalli wrote: > > > In netem_enqueue function the value of skb_headlen(skb) can be zero > > > which leads to a division error during randomized corruption of the packet. > > > This fix adds a check to skb_headlen(skb) to prevent the division error. > > > > > > Crash report: > > > [ 343.170349] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family > > > 0 port 6081 - 0 > > > [ 343.216110] netem: version 1.3 > > > [ 343.235841] divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI > > > [ 343.236680] CPU: 3 PID: 4288 Comm: reproducer Not tainted 5.16.0-rc1+ > > > [ 343.237569] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > > > BIOS 1.11.0-2.el7 04/01/2014 > > > [ 343.238707] RIP: 0010:netem_enqueue+0x1590/0x33c0 [sch_netem] > > > [ 343.239499] Code: 89 85 58 ff ff ff e8 5f 5d e9 d3 48 8b b5 48 ff ff > > > ff 8b 8d 50 ff ff ff 8b 85 58 ff ff ff 48 8b bd 70 ff ff ff 31 d2 2b 4f > > > 74 <f7> f1 48 b8 00 00 00 00 00 fc ff df 49 01 d5 4c 89 e9 48 c1 e9 03 > > > [ 343.241883] RSP: 0018:ffff88800bcd7368 EFLAGS: 00010246 > > > [ 343.242589] RAX: 00000000ba7c0a9c RBX: 0000000000000001 RCX: > > > 0000000000000000 > > > [ 343.243542] RDX: 0000000000000000 RSI: ffff88800f8edb10 RDI: > > > ffff88800f8eda40 > > > [ 343.244474] RBP: ffff88800bcd7458 R08: 0000000000000000 R09: > > > ffffffff94fb8445 > > > [ 343.245403] R10: ffffffff94fb8336 R11: ffffffff94fb8445 R12: > > > 0000000000000000 > > > [ 343.246355] R13: ffff88800a5a7000 R14: ffff88800a5b5800 R15: > > > 0000000000000020 > > > [ 343.247291] FS: 00007fdde2bd7700(0000) GS:ffff888109780000(0000) > > > knlGS:0000000000000000 > > > [ 343.248350] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > [ 343.249120] CR2: 00000000200000c0 CR3: 000000000ef4c000 CR4: > > > 00000000000006e0 > > > [ 343.250076] Call Trace: > > > [ 343.250423] <TASK> > > > [ 343.250713] ? memcpy+0x4d/0x60 > > > [ 343.251162] ? netem_init+0xa0/0xa0 [sch_netem] > > > [ 343.251795] ? __sanitizer_cov_trace_pc+0x21/0x60 > > > [ 343.252443] netem_enqueue+0xe28/0x33c0 [sch_netem] > > > [ 343.253102] ? stack_trace_save+0x87/0xb0 > > > [ 343.253655] ? filter_irq_stacks+0xb0/0xb0 > > > [ 343.254220] ? netem_init+0xa0/0xa0 [sch_netem] > > > [ 343.254837] ? __kasan_check_write+0x14/0x20 > > > [ 343.255418] ? _raw_spin_lock+0x88/0xd6 > > > [ 343.255953] dev_qdisc_enqueue+0x50/0x180 > > > [ 343.256508] __dev_queue_xmit+0x1a7e/0x3090 > > > [ 343.257083] ? netdev_core_pick_tx+0x300/0x300 > > > [ 343.257690] ? check_kcov_mode+0x10/0x40 > > > [ 343.258219] ? _raw_spin_unlock_irqrestore+0x29/0x40 > > > [ 343.258899] ? __kasan_init_slab_obj+0x24/0x30 > > > [ 343.259529] ? setup_object.isra.71+0x23/0x90 > > > [ 343.260121] ? new_slab+0x26e/0x4b0 > > > [ 343.260609] ? kasan_poison+0x3a/0x50 > > > [ 343.261118] ? kasan_unpoison+0x28/0x50 > > > [ 343.261637] ? __kasan_slab_alloc+0x71/0x90 > > > [ 343.262214] ? memcpy+0x4d/0x60 > > > [ 343.262674] ? write_comp_data+0x2f/0x90 > > > [ 343.263209] ? __kasan_check_write+0x14/0x20 > > > [ 343.263802] ? __skb_clone+0x5d6/0x840 > > > [ 343.264329] ? __sanitizer_cov_trace_pc+0x21/0x60 > > > [ 343.264958] dev_queue_xmit+0x1c/0x20 > > > [ 343.265470] netlink_deliver_tap+0x652/0x9c0 > > > [ 343.266067] netlink_unicast+0x5a0/0x7f0 > > > [ 343.266608] ? netlink_attachskb+0x860/0x860 > > > [ 343.267183] ? __sanitizer_cov_trace_pc+0x21/0x60 > > > [ 343.267820] ? write_comp_data+0x2f/0x90 > > > [ 343.268367] netlink_sendmsg+0x922/0xe80 > > > [ 343.268899] ? netlink_unicast+0x7f0/0x7f0 > > > [ 343.269472] ? __sanitizer_cov_trace_pc+0x21/0x60 > > > [ 343.270099] ? write_comp_data+0x2f/0x90 > > > [ 343.270644] ? netlink_unicast+0x7f0/0x7f0 > > > [ 343.271210] sock_sendmsg+0x155/0x190 > > > [ 343.271721] ____sys_sendmsg+0x75f/0x8f0 > > > [ 343.272262] ? kernel_sendmsg+0x60/0x60 > > > [ 343.272788] ? write_comp_data+0x2f/0x90 > > > [ 343.273332] ? write_comp_data+0x2f/0x90 > > > [ 343.273869] ___sys_sendmsg+0x10f/0x190 > > > [ 343.274405] ? sendmsg_copy_msghdr+0x80/0x80 > > > [ 343.274984] ? slab_post_alloc_hook+0x70/0x230 > > > [ 343.275597] ? futex_wait_setup+0x240/0x240 > > > [ 343.276175] ? security_file_alloc+0x3e/0x170 > > > [ 343.276779] ? write_comp_data+0x2f/0x90 > > > [ 343.277313] ? __sanitizer_cov_trace_pc+0x21/0x60 > > > [ 343.277969] ? write_comp_data+0x2f/0x90 > > > [ 343.278515] ? __fget_files+0x1ad/0x260 > > > [ 343.279048] ? __sanitizer_cov_trace_pc+0x21/0x60 > > > [ 343.279685] ? write_comp_data+0x2f/0x90 > > > [ 343.280234] ? __sanitizer_cov_trace_pc+0x21/0x60 > > > [ 343.280874] ? sockfd_lookup_light+0xd1/0x190 > > > [ 343.281481] __sys_sendmsg+0x118/0x200 > > > [ 343.281998] ? __sys_sendmsg_sock+0x40/0x40 > > > [ 343.282578] ? alloc_fd+0x229/0x5e0 > > > [ 343.283070] ? write_comp_data+0x2f/0x90 > > > [ 343.283610] ? write_comp_data+0x2f/0x90 > > > [ 343.284135] ? __sanitizer_cov_trace_pc+0x21/0x60 > > > [ 343.284776] ? ktime_get_coarse_real_ts64+0xb8/0xf0 > > > [ 343.285450] __x64_sys_sendmsg+0x7d/0xc0 > > > [ 343.285981] ? syscall_enter_from_user_mode+0x4d/0x70 > > > [ 343.286664] do_syscall_64+0x3a/0x80 > > > [ 343.287158] entry_SYSCALL_64_after_hwframe+0x44/0xae > > > [ 343.287850] RIP: 0033:0x7fdde24cf289 > > > [ 343.288344] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 > > > 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f > > > 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b7 db 2c 00 f7 d8 64 89 01 48 > > > [ 343.290729] RSP: 002b:00007fdde2bd6d98 EFLAGS: 00000246 ORIG_RAX: > > > 000000000000002e > > > [ 343.291730] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: > > > 00007fdde24cf289 > > > [ 343.292673] RDX: 0000000000000000 RSI: 00000000200000c0 RDI: > > > 0000000000000004 > > > [ 343.293618] RBP: 00007fdde2bd6e20 R08: 0000000100000001 R09: > > > 0000000000000000 > > > [ 343.294557] R10: 0000000100000001 R11: 0000000000000246 R12: > > > 0000000000000000 > > > [ 343.295493] R13: 0000000000021000 R14: 0000000000000000 R15: > > > 00007fdde2bd7700 > > > [ 343.296432] </TASK> > > > [ 343.296735] Modules linked in: sch_netem ip6_vti ip_vti ip_gre ipip > > > sit ip_tunnel geneve macsec macvtap tap ipvlan macvlan 8021q garp mrp > > > hsr wireguard libchacha20poly1305 chacha_x86_64 poly1305_x86_64 > > > ip6_udp_tunnel udp_tunnel libblake2s blake2s_x86_64 libblake2s_generic > > > curve25519_x86_64 libcurve25519_generic libchacha xfrm_interface > > > xfrm6_tunnel tunnel4 veth netdevsim psample batman_adv nlmon dummy team > > > bonding tls vcan ip6_gre ip6_tunnel tunnel6 gre tun ip6t_rpfilter > > > ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set > > > ebtable_nat ebtable_broute ip6table_nat ip6table_mangle > > > ip6table_security ip6table_raw iptable_nat nf_nat nf_conntrack > > > nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle iptable_security > > > iptable_raw ebtable_filter ebtables rfkill ip6table_filter ip6_tables > > > iptable_filter ppdev bochs drm_vram_helper drm_ttm_helper ttm > > > drm_kms_helper cec parport_pc drm joydev floppy parport sg syscopyarea > > > sysfillrect sysimgblt i2c_piix4 qemu_fw_cfg fb_sys_fops pcspkr > > > [ 343.297459] ip_tables xfs virtio_net net_failover failover sd_mod > > > sr_mod cdrom t10_pi ata_generic pata_acpi ata_piix libata virtio_pci > > > virtio_pci_legacy_dev serio_raw virtio_pci_modern_dev dm_mirror > > > dm_region_hash dm_log dm_mod > > > [ 343.311074] Dumping ftrace buffer: > > > [ 343.311532] (ftrace buffer empty) > > > [ 343.312040] ---[ end trace a2e3db5a6ae05099 ]--- > > > [ 343.312691] RIP: 0010:netem_enqueue+0x1590/0x33c0 [sch_netem] > > > [ 343.313481] Code: 89 85 58 ff ff ff e8 5f 5d e9 d3 48 8b b5 48 ff ff > > > ff 8b 8d 50 ff ff ff 8b 85 58 ff ff ff 48 8b bd 70 ff ff ff 31 d2 2b 4f > > > 74 <f7> f1 48 b8 00 00 00 00 00 fc ff df 49 01 d5 4c 89 e9 48 c1 e9 03 > > > [ 343.315893] RSP: 0018:ffff88800bcd7368 EFLAGS: 00010246 > > > [ 343.316622] RAX: 00000000ba7c0a9c RBX: 0000000000000001 RCX: > > > 0000000000000000 > > > [ 343.317585] RDX: 0000000000000000 RSI: ffff88800f8edb10 RDI: > > > ffff88800f8eda40 > > > [ 343.318549] RBP: ffff88800bcd7458 R08: 0000000000000000 R09: > > > ffffffff94fb8445 > > > [ 343.319503] R10: ffffffff94fb8336 R11: ffffffff94fb8445 R12: > > > 0000000000000000 > > > [ 343.320455] R13: ffff88800a5a7000 R14: ffff88800a5b5800 R15: > > > 0000000000000020 > > > [ 343.321414] FS: 00007fdde2bd7700(0000) GS:ffff888109780000(0000) > > > knlGS:0000000000000000 > > > [ 343.322489] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > [ 343.323283] CR2: 00000000200000c0 CR3: 000000000ef4c000 CR4: > > > 00000000000006e0 > > > [ 343.324264] Kernel panic - not syncing: Fatal exception in interrupt > > > [ 343.333717] Dumping ftrace buffer: > > > [ 343.334175] (ftrace buffer empty) > > > [ 343.334653] Kernel Offset: 0x13600000 from 0xffffffff81000000 > > > (relocation range: 0xffffffff80000000-0xffffffffbfffffff) > > > [ 343.336027] Rebooting in 86400 seconds.. > > > > > > Reported-by: syzkaller <syzkaller@googlegroups.com> > > > Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> > > > --- > > > net/sched/sch_netem.c | 10 ++++++++-- > > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > > > diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c > > > index ecbb10db1111..e1e1a00fedda 100644 > > > --- a/net/sched/sch_netem.c > > > +++ b/net/sched/sch_netem.c > > > @@ -513,8 +513,14 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch, > > > goto finish_segs; > > > } > > > > > > - skb->data[prandom_u32() % skb_headlen(skb)] ^= > > > - 1<<(prandom_u32() % 8); > > > + if (unlikely(!skb_headlen(skb))) { > > > + qdisc_drop(skb, sch, to_free); > > > + skb = NULL; > > > + goto finish_segs; > > > + } else { > > > + skb->data[prandom_u32() % skb_headlen(skb)] ^= > > > + 1<<(prandom_u32() % 8); > > > + } > > > } > > > > > > if (unlikely(sch->q.qlen >= sch->limit)) { > > > > > > > > > If we accept the fact that a packet can reach qdisc with nothing in skb->head, > > then we have other serious issues. > > > > Why dropping the packet ? > > > > I would rather pull headers here. > > > > Agree with Eric, would be to just linearize befor the corruption step. > There is also the issue of checksum offload here. Why not just fix network scheduler to drop and warn on zero length skb being queued?
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index ecbb10db1111..e1e1a00fedda 100644 --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -513,8 +513,14 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch, goto finish_segs; } - skb->data[prandom_u32() % skb_headlen(skb)] ^= - 1<<(prandom_u32() % 8); + if (unlikely(!skb_headlen(skb))) { + qdisc_drop(skb, sch, to_free); + skb = NULL; + goto finish_segs; + } else { + skb->data[prandom_u32() % skb_headlen(skb)] ^= + 1<<(prandom_u32() % 8); + } } if (unlikely(sch->q.qlen >= sch->limit)) {
In netem_enqueue function the value of skb_headlen(skb) can be zero which leads to a division error during randomized corruption of the packet. This fix adds a check to skb_headlen(skb) to prevent the division error. Crash report: [ 343.170349] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0 [ 343.216110] netem: version 1.3 [ 343.235841] divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI [ 343.236680] CPU: 3 PID: 4288 Comm: reproducer Not tainted 5.16.0-rc1+ [ 343.237569] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 [ 343.238707] RIP: 0010:netem_enqueue+0x1590/0x33c0 [sch_netem] [ 343.239499] Code: 89 85 58 ff ff ff e8 5f 5d e9 d3 48 8b b5 48 ff ff ff 8b 8d 50 ff ff ff 8b 85 58 ff ff ff 48 8b bd 70 ff ff ff 31 d2 2b 4f 74 <f7> f1 48 b8 00 00 00 00 00 fc ff df 49 01 d5 4c 89 e9 48 c1 e9 03 [ 343.241883] RSP: 0018:ffff88800bcd7368 EFLAGS: 00010246 [ 343.242589] RAX: 00000000ba7c0a9c RBX: 0000000000000001 RCX: 0000000000000000 [ 343.243542] RDX: 0000000000000000 RSI: ffff88800f8edb10 RDI: ffff88800f8eda40 [ 343.244474] RBP: ffff88800bcd7458 R08: 0000000000000000 R09: ffffffff94fb8445 [ 343.245403] R10: ffffffff94fb8336 R11: ffffffff94fb8445 R12: 0000000000000000 [ 343.246355] R13: ffff88800a5a7000 R14: ffff88800a5b5800 R15: 0000000000000020 [ 343.247291] FS: 00007fdde2bd7700(0000) GS:ffff888109780000(0000) knlGS:0000000000000000 [ 343.248350] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 343.249120] CR2: 00000000200000c0 CR3: 000000000ef4c000 CR4: 00000000000006e0 [ 343.250076] Call Trace: [ 343.250423] <TASK> [ 343.250713] ? memcpy+0x4d/0x60 [ 343.251162] ? netem_init+0xa0/0xa0 [sch_netem] [ 343.251795] ? __sanitizer_cov_trace_pc+0x21/0x60 [ 343.252443] netem_enqueue+0xe28/0x33c0 [sch_netem] [ 343.253102] ? stack_trace_save+0x87/0xb0 [ 343.253655] ? filter_irq_stacks+0xb0/0xb0 [ 343.254220] ? netem_init+0xa0/0xa0 [sch_netem] [ 343.254837] ? __kasan_check_write+0x14/0x20 [ 343.255418] ? _raw_spin_lock+0x88/0xd6 [ 343.255953] dev_qdisc_enqueue+0x50/0x180 [ 343.256508] __dev_queue_xmit+0x1a7e/0x3090 [ 343.257083] ? netdev_core_pick_tx+0x300/0x300 [ 343.257690] ? check_kcov_mode+0x10/0x40 [ 343.258219] ? _raw_spin_unlock_irqrestore+0x29/0x40 [ 343.258899] ? __kasan_init_slab_obj+0x24/0x30 [ 343.259529] ? setup_object.isra.71+0x23/0x90 [ 343.260121] ? new_slab+0x26e/0x4b0 [ 343.260609] ? kasan_poison+0x3a/0x50 [ 343.261118] ? kasan_unpoison+0x28/0x50 [ 343.261637] ? __kasan_slab_alloc+0x71/0x90 [ 343.262214] ? memcpy+0x4d/0x60 [ 343.262674] ? write_comp_data+0x2f/0x90 [ 343.263209] ? __kasan_check_write+0x14/0x20 [ 343.263802] ? __skb_clone+0x5d6/0x840 [ 343.264329] ? __sanitizer_cov_trace_pc+0x21/0x60 [ 343.264958] dev_queue_xmit+0x1c/0x20 [ 343.265470] netlink_deliver_tap+0x652/0x9c0 [ 343.266067] netlink_unicast+0x5a0/0x7f0 [ 343.266608] ? netlink_attachskb+0x860/0x860 [ 343.267183] ? __sanitizer_cov_trace_pc+0x21/0x60 [ 343.267820] ? write_comp_data+0x2f/0x90 [ 343.268367] netlink_sendmsg+0x922/0xe80 [ 343.268899] ? netlink_unicast+0x7f0/0x7f0 [ 343.269472] ? __sanitizer_cov_trace_pc+0x21/0x60 [ 343.270099] ? write_comp_data+0x2f/0x90 [ 343.270644] ? netlink_unicast+0x7f0/0x7f0 [ 343.271210] sock_sendmsg+0x155/0x190 [ 343.271721] ____sys_sendmsg+0x75f/0x8f0 [ 343.272262] ? kernel_sendmsg+0x60/0x60 [ 343.272788] ? write_comp_data+0x2f/0x90 [ 343.273332] ? write_comp_data+0x2f/0x90 [ 343.273869] ___sys_sendmsg+0x10f/0x190 [ 343.274405] ? sendmsg_copy_msghdr+0x80/0x80 [ 343.274984] ? slab_post_alloc_hook+0x70/0x230 [ 343.275597] ? futex_wait_setup+0x240/0x240 [ 343.276175] ? security_file_alloc+0x3e/0x170 [ 343.276779] ? write_comp_data+0x2f/0x90 [ 343.277313] ? __sanitizer_cov_trace_pc+0x21/0x60 [ 343.277969] ? write_comp_data+0x2f/0x90 [ 343.278515] ? __fget_files+0x1ad/0x260 [ 343.279048] ? __sanitizer_cov_trace_pc+0x21/0x60 [ 343.279685] ? write_comp_data+0x2f/0x90 [ 343.280234] ? __sanitizer_cov_trace_pc+0x21/0x60 [ 343.280874] ? sockfd_lookup_light+0xd1/0x190 [ 343.281481] __sys_sendmsg+0x118/0x200 [ 343.281998] ? __sys_sendmsg_sock+0x40/0x40 [ 343.282578] ? alloc_fd+0x229/0x5e0 [ 343.283070] ? write_comp_data+0x2f/0x90 [ 343.283610] ? write_comp_data+0x2f/0x90 [ 343.284135] ? __sanitizer_cov_trace_pc+0x21/0x60 [ 343.284776] ? ktime_get_coarse_real_ts64+0xb8/0xf0 [ 343.285450] __x64_sys_sendmsg+0x7d/0xc0 [ 343.285981] ? syscall_enter_from_user_mode+0x4d/0x70 [ 343.286664] do_syscall_64+0x3a/0x80 [ 343.287158] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 343.287850] RIP: 0033:0x7fdde24cf289 [ 343.288344] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b7 db 2c 00 f7 d8 64 89 01 48 [ 343.290729] RSP: 002b:00007fdde2bd6d98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 343.291730] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdde24cf289 [ 343.292673] RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000004 [ 343.293618] RBP: 00007fdde2bd6e20 R08: 0000000100000001 R09: 0000000000000000 [ 343.294557] R10: 0000000100000001 R11: 0000000000000246 R12: 0000000000000000 [ 343.295493] R13: 0000000000021000 R14: 0000000000000000 R15: 00007fdde2bd7700 [ 343.296432] </TASK> [ 343.296735] Modules linked in: sch_netem ip6_vti ip_vti ip_gre ipip sit ip_tunnel geneve macsec macvtap tap ipvlan macvlan 8021q garp mrp hsr wireguard libchacha20poly1305 chacha_x86_64 poly1305_x86_64 ip6_udp_tunnel udp_tunnel libblake2s blake2s_x86_64 libblake2s_generic curve25519_x86_64 libcurve25519_generic libchacha xfrm_interface xfrm6_tunnel tunnel4 veth netdevsim psample batman_adv nlmon dummy team bonding tls vcan ip6_gre ip6_tunnel tunnel6 gre tun ip6t_rpfilter ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set ebtable_nat ebtable_broute ip6table_nat ip6table_mangle ip6table_security ip6table_raw iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle iptable_security iptable_raw ebtable_filter ebtables rfkill ip6table_filter ip6_tables iptable_filter ppdev bochs drm_vram_helper drm_ttm_helper ttm drm_kms_helper cec parport_pc drm joydev floppy parport sg syscopyarea sysfillrect sysimgblt i2c_piix4 qemu_fw_cfg fb_sys_fops pcspkr [ 343.297459] ip_tables xfs virtio_net net_failover failover sd_mod sr_mod cdrom t10_pi ata_generic pata_acpi ata_piix libata virtio_pci virtio_pci_legacy_dev serio_raw virtio_pci_modern_dev dm_mirror dm_region_hash dm_log dm_mod [ 343.311074] Dumping ftrace buffer: [ 343.311532] (ftrace buffer empty) [ 343.312040] ---[ end trace a2e3db5a6ae05099 ]--- [ 343.312691] RIP: 0010:netem_enqueue+0x1590/0x33c0 [sch_netem] [ 343.313481] Code: 89 85 58 ff ff ff e8 5f 5d e9 d3 48 8b b5 48 ff ff ff 8b 8d 50 ff ff ff 8b 85 58 ff ff ff 48 8b bd 70 ff ff ff 31 d2 2b 4f 74 <f7> f1 48 b8 00 00 00 00 00 fc ff df 49 01 d5 4c 89 e9 48 c1 e9 03 [ 343.315893] RSP: 0018:ffff88800bcd7368 EFLAGS: 00010246 [ 343.316622] RAX: 00000000ba7c0a9c RBX: 0000000000000001 RCX: 0000000000000000 [ 343.317585] RDX: 0000000000000000 RSI: ffff88800f8edb10 RDI: ffff88800f8eda40 [ 343.318549] RBP: ffff88800bcd7458 R08: 0000000000000000 R09: ffffffff94fb8445 [ 343.319503] R10: ffffffff94fb8336 R11: ffffffff94fb8445 R12: 0000000000000000 [ 343.320455] R13: ffff88800a5a7000 R14: ffff88800a5b5800 R15: 0000000000000020 [ 343.321414] FS: 00007fdde2bd7700(0000) GS:ffff888109780000(0000) knlGS:0000000000000000 [ 343.322489] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 343.323283] CR2: 00000000200000c0 CR3: 000000000ef4c000 CR4: 00000000000006e0 [ 343.324264] Kernel panic - not syncing: Fatal exception in interrupt [ 343.333717] Dumping ftrace buffer: [ 343.334175] (ftrace buffer empty) [ 343.334653] Kernel Offset: 0x13600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 343.336027] Rebooting in 86400 seconds.. Reported-by: syzkaller <syzkaller@googlegroups.com> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> --- net/sched/sch_netem.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)