| Message ID | 20241204170548.4152658-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | b04d86fff66b15c07505d226431f808c15b1703c |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] tipc: fix NULL deref in cleanup_bearer() | expand |
From: Eric Dumazet <edumazet@google.com> Date: Wed, 4 Dec 2024 17:05:48 +0000 > syzbot found [1] that after blamed commit, ub->ubsock->sk > was NULL when attempting the atomic_dec() : > > atomic_dec(&tipc_net(sock_net(ub->ubsock->sk))->wq_count); > > Fix this by caching the tipc_net pointer. > > [1] > > Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN PTI > KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] > CPU: 0 UID: 0 PID: 5896 Comm: kworker/0:3 Not tainted 6.13.0-rc1-next-20241203-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 > Workqueue: events cleanup_bearer > RIP: 0010:read_pnet include/net/net_namespace.h:387 [inline] > RIP: 0010:sock_net include/net/sock.h:655 [inline] > RIP: 0010:cleanup_bearer+0x1f7/0x280 net/tipc/udp_media.c:820 > Code: 18 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 3c f7 99 f6 48 8b 1b 48 83 c3 30 e8 f0 e4 60 00 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 1a f7 99 f6 49 83 c7 e8 48 8b 1b > RSP: 0018:ffffc9000410fb70 EFLAGS: 00010206 > RAX: 0000000000000006 RBX: 0000000000000030 RCX: ffff88802fe45a00 > RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9000410f900 > RBP: ffff88807e1f0908 R08: ffffc9000410f907 R09: 1ffff92000821f20 > R10: dffffc0000000000 R11: fffff52000821f21 R12: ffff888031d19980 > R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff88807e1f0918 > FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000556ca050b000 CR3: 0000000031c0c000 CR4: 00000000003526f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Fixes: 6a2fa13312e5 ("tipc: Fix use-after-free of kernel socket in cleanup_bearer().") > Reported-by: syzbot+46aa5474f179dacd1a3b@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/67508b5f.050a0220.17bd51.0070.GAE@google.com/T/#u > Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Thanks!
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Wed, 4 Dec 2024 17:05:48 +0000 you wrote: > syzbot found [1] that after blamed commit, ub->ubsock->sk > was NULL when attempting the atomic_dec() : > > atomic_dec(&tipc_net(sock_net(ub->ubsock->sk))->wq_count); > > Fix this by caching the tipc_net pointer. > > [...] Here is the summary with links: - [net] tipc: fix NULL deref in cleanup_bearer() https://git.kernel.org/netdev/net/c/b04d86fff66b You are awesome, thank you!
diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c index b7e25e7e9933b69aa6a3364e3287c358b7ac9421..108a4cc2e001077169a4e4c3bebd42715db9a803 100644 --- a/net/tipc/udp_media.c +++ b/net/tipc/udp_media.c @@ -807,6 +807,7 @@ static void cleanup_bearer(struct work_struct *work) { struct udp_bearer *ub = container_of(work, struct udp_bearer, work); struct udp_replicast *rcast, *tmp; + struct tipc_net *tn; list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) { dst_cache_destroy(&rcast->dst_cache); @@ -814,10 +815,14 @@ static void cleanup_bearer(struct work_struct *work) kfree_rcu(rcast, rcu); } + tn = tipc_net(sock_net(ub->ubsock->sk)); + dst_cache_destroy(&ub->rcast.dst_cache); udp_tunnel_sock_release(ub->ubsock); + + /* Note: could use a call_rcu() to avoid another synchronize_net() */ synchronize_net(); - atomic_dec(&tipc_net(sock_net(ub->ubsock->sk))->wq_count); + atomic_dec(&tn->wq_count); kfree(ub); }
syzbot found [1] that after blamed commit, ub->ubsock->sk was NULL when attempting the atomic_dec() : atomic_dec(&tipc_net(sock_net(ub->ubsock->sk))->wq_count); Fix this by caching the tipc_net pointer. [1] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] CPU: 0 UID: 0 PID: 5896 Comm: kworker/0:3 Not tainted 6.13.0-rc1-next-20241203-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events cleanup_bearer RIP: 0010:read_pnet include/net/net_namespace.h:387 [inline] RIP: 0010:sock_net include/net/sock.h:655 [inline] RIP: 0010:cleanup_bearer+0x1f7/0x280 net/tipc/udp_media.c:820 Code: 18 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 3c f7 99 f6 48 8b 1b 48 83 c3 30 e8 f0 e4 60 00 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 1a f7 99 f6 49 83 c7 e8 48 8b 1b RSP: 0018:ffffc9000410fb70 EFLAGS: 00010206 RAX: 0000000000000006 RBX: 0000000000000030 RCX: ffff88802fe45a00 RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9000410f900 RBP: ffff88807e1f0908 R08: ffffc9000410f907 R09: 1ffff92000821f20 R10: dffffc0000000000 R11: fffff52000821f21 R12: ffff888031d19980 R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff88807e1f0918 FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000556ca050b000 CR3: 0000000031c0c000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Fixes: 6a2fa13312e5 ("tipc: Fix use-after-free of kernel socket in cleanup_bearer().") Reported-by: syzbot+46aa5474f179dacd1a3b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/67508b5f.050a0220.17bd51.0070.GAE@google.com/T/#u Signed-off-by: Eric Dumazet <edumazet@google.com> --- Cc: Kuniyuki Iwashima <kuniyu@amazon.com> --- net/tipc/udp_media.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)