Re: [PATCH v1 net] net: Remove WARN_ON_ONCE(sk->sk_forward_alloc) from sk_stream_kill_queues().
From: Eric Dumazet <edumazet@google.com>
Date: 2023-02-07 19:25:42
On Tue, Feb 7, 2023 at 7:37 PM Kuniyuki Iwashima [off-list ref] wrote:
In commit b5fc29233d28 ("inet6: Remove inet6_destroy_sock() in
sk->sk_prot->destroy()."), we delay freeing some IPv6 resources
from sk->destroy() to sk->sk_destruct().
Christoph Paasch reported the commit started triggering
WARN_ON_ONCE(sk->sk_forward_alloc) in sk_stream_kill_queues()
(See [0 - 2]).
For example, if inet6_sk(sk)->rxopt is not zero by setting
IPV6_RECVPKTINFO or its friends, tcp_v6_do_rcv() clones a skb
and calls skb_set_owner_r(), which charges it to sk.skb_set_owner_r() in this place seems wrong. This could lead to a negative sk->sk_forward_alloc (because we have not sk_rmem_schedule() it ?) Do you have a repro ? The skb
quoted hunk ↗ jump to hunk
has not been uncharged in inet_csk_destroy_sock(), thus, calling sk_stream_kill_queues() there triggers the WARN_ON_ONCE(). The same check has been in inet_sock_destruct() from at least v2.6. Since only CAIF is not calling inet_sock_destruct() among the users of sk_stream_kill_queues(), we remove the WARN_ON_ONCE() from sk_stream_kill_queues() and add it to caif_sock_destructor(). [0]: https://lore.kernel.org/netdev/39725AB4-88F1-41B3-B07F-949C5CAEFF4F@icloud.com/ (local) [1]: https://github.com/multipath-tcp/mptcp_net-next/issues/341 [2]: WARNING: CPU: 0 PID: 3232 at net/core/stream.c:212 sk_stream_kill_queues+0x2f9/0x3e0 Modules linked in: CPU: 0 PID: 3232 Comm: syz-executor.0 Not tainted 6.2.0-rc5ab24eb4698afbe147b424149c529e2a43ec24eb5 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:sk_stream_kill_queues+0x2f9/0x3e0 Code: 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e ec 00 00 00 8b ab 08 01 00 00 e9 60 ff ff ff e8 d0 5f b6 fe 0f 0b eb 97 e8 c7 5f b6 fe <0f> 0b eb a0 e8 be 5f b6 fe 0f 0b e9 6a fe ff ff e8 02 07 e3 fe e9 RSP: 0018:ffff88810570fc68 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888101f38f40 RSI: ffffffff8285e529 RDI: 0000000000000005 RBP: 0000000000000ce0 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000ce0 R11: 0000000000000001 R12: ffff8881009e9488 R13: ffffffff84af2cc0 R14: 0000000000000000 R15: ffff8881009e9458 FS: 00007f7fdfbd5800(0000) GS:ffff88811b600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b32923000 CR3: 00000001062fc006 CR4: 0000000000170ef0 Call Trace: <TASK> inet_csk_destroy_sock+0x1a1/0x320 __tcp_close+0xab6/0xe90 tcp_close+0x30/0xc0 inet_release+0xe9/0x1f0 inet6_release+0x4c/0x70 __sock_release+0xd2/0x280 sock_close+0x15/0x20 __fput+0x252/0xa20 task_work_run+0x169/0x250 exit_to_user_mode_prepare+0x113/0x120 syscall_exit_to_user_mode+0x1d/0x40 do_syscall_64+0x48/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7f7fdf7ae28d Code: c1 20 00 00 75 10 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ee fb ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 37 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00000000007dfbb0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f7fdf7ae28d RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000003 RBP: 0000000000000000 R08: 000000007f338e0f R09: 0000000000000e0f R10: 000000007f338e13 R11: 0000000000000293 R12: 00007f7fdefff000 R13: 00007f7fdefffcd8 R14: 00007f7fdefffce0 R15: 00007f7fdefffcd8 </TASK> Fixes: b5fc29233d28 ("inet6: Remove inet6_destroy_sock() in sk->sk_prot->destroy().") Reported-by: syzbot <redacted> Reported-by: Christoph Paasch <redacted> Signed-off-by: Kuniyuki Iwashima <redacted> --- net/caif/caif_socket.c | 1 + net/core/stream.c | 1 - 2 files changed, 1 insertion(+), 1 deletion(-)diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c index 748be7253248..78c9729a6057 100644 --- a/net/caif/caif_socket.c +++ b/net/caif/caif_socket.c@@ -1015,6 +1015,7 @@ static void caif_sock_destructor(struct sock *sk) return; } sk_stream_kill_queues(&cf_sk->sk); + WARN_ON_ONCE(sk->sk_forward_alloc); caif_free_client(&cf_sk->layer); }diff --git a/net/core/stream.c b/net/core/stream.c index cd06750dd329..434446ab14c5 100644 --- a/net/core/stream.c +++ b/net/core/stream.c@@ -209,7 +209,6 @@ void sk_stream_kill_queues(struct sock *sk) sk_mem_reclaim_final(sk); WARN_ON_ONCE(sk->sk_wmem_queued); - WARN_ON_ONCE(sk->sk_forward_alloc); /* It is _impossible_ for the backlog to contain anything * when we get here. All user references to this socket --2.30.2