diff mbox series

[net-next] ip6_tunnel: fix possible NULL deref in ip6_tnl_xmit

Message ID 20220208214148.3282081-1-eric.dumazet@gmail.com (mailing list archive)
State Accepted
Commit 3a5f238f2b369817f94956cad9cc76924278578c
Delegated to: Netdev Maintainers
Headers show
Series [net-next] ip6_tunnel: fix possible NULL deref in ip6_tnl_xmit | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 1 maintainers not CCed: yoshfuji@linux-ipv6.org
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch warning WARNING: Possible repeated word: 'Google'
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Eric Dumazet Feb. 8, 2022, 9:41 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

Make sure to test that skb has a dst attached to it.

general protection fault, probably for non-canonical address 0xdffffc0000000011: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f]
CPU: 0 PID: 32650 Comm: syz-executor.4 Not tainted 5.17.0-rc2-next-20220204-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ip6_tnl_xmit+0x2140/0x35f0 net/ipv6/ip6_tunnel.c:1127
Code: 4d 85 f6 0f 85 c5 04 00 00 e8 9c b0 66 f9 48 83 e3 fe 48 b8 00 00 00 00 00 fc ff df 48 8d bb 88 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 07 7f 05 e8 11 25 b2 f9 44 0f b6 b3 88 00 00
RSP: 0018:ffffc900141b7310 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc9000c77a000
RDX: 0000000000000011 RSI: ffffffff8811f854 RDI: 0000000000000088
RBP: ffffc900141b7480 R08: 0000000000000000 R09: 0000000000000008
R10: ffffffff8811f846 R11: 0000000000000008 R12: ffffc900141b7548
R13: ffff8880297c6000 R14: 0000000000000000 R15: ffff8880351c8dc0
FS:  00007f9827ba2700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31322000 CR3: 0000000033a70000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1386 [inline]
 ip6_tnl_start_xmit+0x71e/0x1830 net/ipv6/ip6_tunnel.c:1435
 __netdev_start_xmit include/linux/netdevice.h:4683 [inline]
 netdev_start_xmit include/linux/netdevice.h:4697 [inline]
 xmit_one net/core/dev.c:3473 [inline]
 dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3489
 __dev_queue_xmit+0x2a24/0x3760 net/core/dev.c:4116
 packet_snd net/packet/af_packet.c:3057 [inline]
 packet_sendmsg+0x2265/0x5460 net/packet/af_packet.c:3084
 sock_sendmsg_nosec net/socket.c:705 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:725
 sock_write_iter+0x289/0x3c0 net/socket.c:1061
 call_write_iter include/linux/fs.h:2075 [inline]
 do_iter_readv_writev+0x47a/0x750 fs/read_write.c:726
 do_iter_write+0x188/0x710 fs/read_write.c:852
 vfs_writev+0x1aa/0x630 fs/read_write.c:925
 do_writev+0x27f/0x300 fs/read_write.c:968
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f9828c2d059

Fixes: c1f55c5e0482 ("ip6_tunnel: allow routing IPv4 traffic in NBMA mode")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Qing Deng <i@moy.cat>
Reported-by: syzbot <syzkaller@googlegroups.com>
---
 net/ipv6/ip6_tunnel.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

patchwork-bot+netdevbpf@kernel.org Feb. 9, 2022, noon UTC | #1 
Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:

On Tue,  8 Feb 2022 13:41:48 -0800 you wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> Make sure to test that skb has a dst attached to it.
> 
> general protection fault, probably for non-canonical address 0xdffffc0000000011: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f]
> CPU: 0 PID: 32650 Comm: syz-executor.4 Not tainted 5.17.0-rc2-next-20220204-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:ip6_tnl_xmit+0x2140/0x35f0 net/ipv6/ip6_tunnel.c:1127
> Code: 4d 85 f6 0f 85 c5 04 00 00 e8 9c b0 66 f9 48 83 e3 fe 48 b8 00 00 00 00 00 fc ff df 48 8d bb 88 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 07 7f 05 e8 11 25 b2 f9 44 0f b6 b3 88 00 00
> RSP: 0018:ffffc900141b7310 EFLAGS: 00010206
> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc9000c77a000
> RDX: 0000000000000011 RSI: ffffffff8811f854 RDI: 0000000000000088
> RBP: ffffc900141b7480 R08: 0000000000000000 R09: 0000000000000008
> R10: ffffffff8811f846 R11: 0000000000000008 R12: ffffc900141b7548
> R13: ffff8880297c6000 R14: 0000000000000000 R15: ffff8880351c8dc0
> FS:  00007f9827ba2700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b31322000 CR3: 0000000033a70000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1386 [inline]
>  ip6_tnl_start_xmit+0x71e/0x1830 net/ipv6/ip6_tunnel.c:1435
>  __netdev_start_xmit include/linux/netdevice.h:4683 [inline]
>  netdev_start_xmit include/linux/netdevice.h:4697 [inline]
>  xmit_one net/core/dev.c:3473 [inline]
>  dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3489
>  __dev_queue_xmit+0x2a24/0x3760 net/core/dev.c:4116
>  packet_snd net/packet/af_packet.c:3057 [inline]
>  packet_sendmsg+0x2265/0x5460 net/packet/af_packet.c:3084
>  sock_sendmsg_nosec net/socket.c:705 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:725
>  sock_write_iter+0x289/0x3c0 net/socket.c:1061
>  call_write_iter include/linux/fs.h:2075 [inline]
>  do_iter_readv_writev+0x47a/0x750 fs/read_write.c:726
>  do_iter_write+0x188/0x710 fs/read_write.c:852
>  vfs_writev+0x1aa/0x630 fs/read_write.c:925
>  do_writev+0x27f/0x300 fs/read_write.c:968
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f9828c2d059
> 
> [...]

Here is the summary with links:
  - [net-next] ip6_tunnel: fix possible NULL deref in ip6_tnl_xmit
    https://git.kernel.org/netdev/net-next/c/3a5f238f2b36

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index b47ffc81f9e51f152608c22c1c02d9ababf99137..53f632a560ec2019a73b35a61ea24a219a4a49c7 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1122,7 +1122,10 @@  int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield,
 			memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));
 			neigh_release(neigh);
 		} else if (skb->protocol == htons(ETH_P_IP)) {
-			struct rtable *rt = skb_rtable(skb);
+			const struct rtable *rt = skb_rtable(skb);
+
+			if (!rt)
+				goto tx_err_link_failure;
 
 			if (rt->rt_gw_family == AF_INET6)
 				memcpy(&fl6->daddr, &rt->rt_gw6, sizeof(fl6->daddr));