| Message ID | 20240903140708.3122263-3-dmantipov@yandex.ru (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v4,1/3] net: sched: fix use-after-free in taprio_change() | expand |
On Tue, Sep 03, 2024 at 05:07:08PM +0300, Dmitry Antipov wrote: > Fix possible use-after-free in 'taprio_dump()' by adding RCU > read-side critical section there. Never seen on x86 but > found on a KASAN-enabled arm64 system when investigating > https://syzkaller.appspot.com/bug?extid=b65e0af58423fc8a73aa: > > [T15862] BUG: KASAN: slab-use-after-free in taprio_dump+0xa0c/0xbb0 > [T15862] Read of size 4 at addr ffff0000d4bb88f8 by task repro/15862 > [T15862] > [T15862] CPU: 0 UID: 0 PID: 15862 Comm: repro Not tainted 6.11.0-rc1-00293-gdefaf1a2113a-dirty #2 > [T15862] Hardware name: QEMU QEMU Virtual Machine, BIOS edk2-20240524-5.fc40 05/24/2024 > [T15862] Call trace: > [T15862] dump_backtrace+0x20c/0x220 > [T15862] show_stack+0x2c/0x40 > [T15862] dump_stack_lvl+0xf8/0x174 > [T15862] print_report+0x170/0x4d8 > [T15862] kasan_report+0xb8/0x1d4 > [T15862] __asan_report_load4_noabort+0x20/0x2c > [T15862] taprio_dump+0xa0c/0xbb0 > [T15862] tc_fill_qdisc+0x540/0x1020 > [T15862] qdisc_notify.isra.0+0x330/0x3a0 > [T15862] tc_modify_qdisc+0x7b8/0x1838 > [T15862] rtnetlink_rcv_msg+0x3c8/0xc20 > [T15862] netlink_rcv_skb+0x1f8/0x3d4 > [T15862] rtnetlink_rcv+0x28/0x40 > [T15862] netlink_unicast+0x51c/0x790 > [T15862] netlink_sendmsg+0x79c/0xc20 > [T15862] __sock_sendmsg+0xe0/0x1a0 > [T15862] ____sys_sendmsg+0x6c0/0x840 > [T15862] ___sys_sendmsg+0x1ac/0x1f0 > [T15862] __sys_sendmsg+0x110/0x1d0 > [T15862] __arm64_sys_sendmsg+0x74/0xb0 > [T15862] invoke_syscall+0x88/0x2e0 > [T15862] el0_svc_common.constprop.0+0xe4/0x2a0 > [T15862] do_el0_svc+0x44/0x60 > [T15862] el0_svc+0x50/0x184 > [T15862] el0t_64_sync_handler+0x120/0x12c > [T15862] el0t_64_sync+0x190/0x194 > [T15862] > [T15862] Allocated by task 15857: > [T15862] kasan_save_stack+0x3c/0x70 > [T15862] kasan_save_track+0x20/0x3c > [T15862] kasan_save_alloc_info+0x40/0x60 > [T15862] __kasan_kmalloc+0xd4/0xe0 > [T15862] __kmalloc_cache_noprof+0x194/0x334 > [T15862] taprio_change+0x45c/0x2fe0 > [T15862] tc_modify_qdisc+0x6a8/0x1838 > [T15862] rtnetlink_rcv_msg+0x3c8/0xc20 > [T15862] netlink_rcv_skb+0x1f8/0x3d4 > [T15862] rtnetlink_rcv+0x28/0x40 > [T15862] netlink_unicast+0x51c/0x790 > [T15862] netlink_sendmsg+0x79c/0xc20 > [T15862] __sock_sendmsg+0xe0/0x1a0 > [T15862] ____sys_sendmsg+0x6c0/0x840 > [T15862] ___sys_sendmsg+0x1ac/0x1f0 > [T15862] __sys_sendmsg+0x110/0x1d0 > [T15862] __arm64_sys_sendmsg+0x74/0xb0 > [T15862] invoke_syscall+0x88/0x2e0 > [T15862] el0_svc_common.constprop.0+0xe4/0x2a0 > [T15862] do_el0_svc+0x44/0x60 > [T15862] el0_svc+0x50/0x184 > [T15862] el0t_64_sync_handler+0x120/0x12c > [T15862] el0t_64_sync+0x190/0x194 > [T15862] > [T15862] Freed by task 6192: > [T15862] kasan_save_stack+0x3c/0x70 > [T15862] kasan_save_track+0x20/0x3c > [T15862] kasan_save_free_info+0x4c/0x80 > [T15862] poison_slab_object+0x110/0x160 > [T15862] __kasan_slab_free+0x3c/0x74 > [T15862] kfree+0x134/0x3c0 > [T15862] taprio_free_sched_cb+0x18c/0x220 > [T15862] rcu_core+0x920/0x1b7c > [T15862] rcu_core_si+0x10/0x1c > [T15862] handle_softirqs+0x2e8/0xd64 > [T15862] __do_softirq+0x14/0x20 > Hi Dmitry, As a fix for net, there should be a Fixes tag here, indicating the first commit in which this bug manifested. This can be the first commit in the tree, if the bug has been there since then. If the patch-set is not going to be resent, it is probably sufficient to just reply with one here. And it may be a good idea to do so regardless. > Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 9f4e004cdb8b..8623dc0bafc0 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -2374,9 +2374,6 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb) struct tc_mqprio_qopt opt = { 0 }; struct nlattr *nest, *sched_nest; - oper = rtnl_dereference(q->oper_sched); - admin = rtnl_dereference(q->admin_sched); - mqprio_qopt_reconstruct(dev, &opt); nest = nla_nest_start_noflag(skb, TCA_OPTIONS); @@ -2397,18 +2394,23 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb) nla_put_u32(skb, TCA_TAPRIO_ATTR_TXTIME_DELAY, q->txtime_delay)) goto options_error; + rcu_read_lock(); + + oper = rtnl_dereference(q->oper_sched); + admin = rtnl_dereference(q->admin_sched); + if (oper && taprio_dump_tc_entries(skb, q, oper)) - goto options_error; + goto options_error_rcu; if (oper && dump_schedule(skb, oper)) - goto options_error; + goto options_error_rcu; if (!admin) goto done; sched_nest = nla_nest_start_noflag(skb, TCA_TAPRIO_ATTR_ADMIN_SCHED); if (!sched_nest) - goto options_error; + goto options_error_rcu; if (dump_schedule(skb, admin)) goto admin_error; @@ -2416,11 +2418,15 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb) nla_nest_end(skb, sched_nest); done: + rcu_read_unlock(); return nla_nest_end(skb, nest); admin_error: nla_nest_cancel(skb, sched_nest); +options_error_rcu: + rcu_read_unlock(); + options_error: nla_nest_cancel(skb, nest);
Fix possible use-after-free in 'taprio_dump()' by adding RCU read-side critical section there. Never seen on x86 but found on a KASAN-enabled arm64 system when investigating https://syzkaller.appspot.com/bug?extid=b65e0af58423fc8a73aa: [T15862] BUG: KASAN: slab-use-after-free in taprio_dump+0xa0c/0xbb0 [T15862] Read of size 4 at addr ffff0000d4bb88f8 by task repro/15862 [T15862] [T15862] CPU: 0 UID: 0 PID: 15862 Comm: repro Not tainted 6.11.0-rc1-00293-gdefaf1a2113a-dirty #2 [T15862] Hardware name: QEMU QEMU Virtual Machine, BIOS edk2-20240524-5.fc40 05/24/2024 [T15862] Call trace: [T15862] dump_backtrace+0x20c/0x220 [T15862] show_stack+0x2c/0x40 [T15862] dump_stack_lvl+0xf8/0x174 [T15862] print_report+0x170/0x4d8 [T15862] kasan_report+0xb8/0x1d4 [T15862] __asan_report_load4_noabort+0x20/0x2c [T15862] taprio_dump+0xa0c/0xbb0 [T15862] tc_fill_qdisc+0x540/0x1020 [T15862] qdisc_notify.isra.0+0x330/0x3a0 [T15862] tc_modify_qdisc+0x7b8/0x1838 [T15862] rtnetlink_rcv_msg+0x3c8/0xc20 [T15862] netlink_rcv_skb+0x1f8/0x3d4 [T15862] rtnetlink_rcv+0x28/0x40 [T15862] netlink_unicast+0x51c/0x790 [T15862] netlink_sendmsg+0x79c/0xc20 [T15862] __sock_sendmsg+0xe0/0x1a0 [T15862] ____sys_sendmsg+0x6c0/0x840 [T15862] ___sys_sendmsg+0x1ac/0x1f0 [T15862] __sys_sendmsg+0x110/0x1d0 [T15862] __arm64_sys_sendmsg+0x74/0xb0 [T15862] invoke_syscall+0x88/0x2e0 [T15862] el0_svc_common.constprop.0+0xe4/0x2a0 [T15862] do_el0_svc+0x44/0x60 [T15862] el0_svc+0x50/0x184 [T15862] el0t_64_sync_handler+0x120/0x12c [T15862] el0t_64_sync+0x190/0x194 [T15862] [T15862] Allocated by task 15857: [T15862] kasan_save_stack+0x3c/0x70 [T15862] kasan_save_track+0x20/0x3c [T15862] kasan_save_alloc_info+0x40/0x60 [T15862] __kasan_kmalloc+0xd4/0xe0 [T15862] __kmalloc_cache_noprof+0x194/0x334 [T15862] taprio_change+0x45c/0x2fe0 [T15862] tc_modify_qdisc+0x6a8/0x1838 [T15862] rtnetlink_rcv_msg+0x3c8/0xc20 [T15862] netlink_rcv_skb+0x1f8/0x3d4 [T15862] rtnetlink_rcv+0x28/0x40 [T15862] netlink_unicast+0x51c/0x790 [T15862] netlink_sendmsg+0x79c/0xc20 [T15862] __sock_sendmsg+0xe0/0x1a0 [T15862] ____sys_sendmsg+0x6c0/0x840 [T15862] ___sys_sendmsg+0x1ac/0x1f0 [T15862] __sys_sendmsg+0x110/0x1d0 [T15862] __arm64_sys_sendmsg+0x74/0xb0 [T15862] invoke_syscall+0x88/0x2e0 [T15862] el0_svc_common.constprop.0+0xe4/0x2a0 [T15862] do_el0_svc+0x44/0x60 [T15862] el0_svc+0x50/0x184 [T15862] el0t_64_sync_handler+0x120/0x12c [T15862] el0t_64_sync+0x190/0x194 [T15862] [T15862] Freed by task 6192: [T15862] kasan_save_stack+0x3c/0x70 [T15862] kasan_save_track+0x20/0x3c [T15862] kasan_save_free_info+0x4c/0x80 [T15862] poison_slab_object+0x110/0x160 [T15862] __kasan_slab_free+0x3c/0x74 [T15862] kfree+0x134/0x3c0 [T15862] taprio_free_sched_cb+0x18c/0x220 [T15862] rcu_core+0x920/0x1b7c [T15862] rcu_core_si+0x10/0x1c [T15862] handle_softirqs+0x2e8/0xd64 [T15862] __do_softirq+0x14/0x20 Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru> --- v4: redesign to preserve original code as much as possible, adjust commit message and subject to target net tree v3: tweak commit message as suggested by Vinicius v2: added to the series --- net/sched/sch_taprio.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)