This is a note to let you know that I've just added the patch titled
mptcp: error out earlier on disconnect
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mptcp-error-out-earlier-on-disconnect.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e15a0ac941898394f13eb736cb6496824613b06b
Author: Paolo Abeni <pabeni@xxxxxxxxxx>
Date: Fri Nov 8 11:58:16 2024 +0100
mptcp: error out earlier on disconnect
[ Upstream commit 581302298524e9d77c4c44ff5156a6cd112227ae ]
Eric reported a division by zero splat in the MPTCP protocol:
Oops: divide error: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 UID: 0 PID: 6094 Comm: syz-executor317 Not tainted
6.12.0-rc5-syzkaller-00291-g05b92660cdfe #0
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 09/13/2024
RIP: 0010:__tcp_select_window+0x5b4/0x1310 net/ipv4/tcp_output.c:3163
Code: f6 44 01 e3 89 df e8 9b 75 09 f8 44 39 f3 0f 8d 11 ff ff ff e8
0d 74 09 f8 45 89 f4 e9 04 ff ff ff e8 00 74 09 f8 44 89 f0 99 <f7> 7c
24 14 41 29 d6 45 89 f4 e9 ec fe ff ff e8 e8 73 09 f8 48 89
RSP: 0018:ffffc900041f7930 EFLAGS: 00010293
RAX: 0000000000017e67 RBX: 0000000000017e67 RCX: ffffffff8983314b
RDX: 0000000000000000 RSI: ffffffff898331b0 RDI: 0000000000000004
RBP: 00000000005d6000 R08: 0000000000000004 R09: 0000000000017e67
R10: 0000000000003e80 R11: 0000000000000000 R12: 0000000000003e80
R13: ffff888031d9b440 R14: 0000000000017e67 R15: 00000000002eb000
FS: 00007feb5d7f16c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007feb5d8adbb8 CR3: 0000000074e4c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__tcp_cleanup_rbuf+0x3e7/0x4b0 net/ipv4/tcp.c:1493
mptcp_rcv_space_adjust net/mptcp/protocol.c:2085 [inline]
mptcp_recvmsg+0x2156/0x2600 net/mptcp/protocol.c:2289
inet_recvmsg+0x469/0x6a0 net/ipv4/af_inet.c:885
sock_recvmsg_nosec net/socket.c:1051 [inline]
sock_recvmsg+0x1b2/0x250 net/socket.c:1073
__sys_recvfrom+0x1a5/0x2e0 net/socket.c:2265
__do_sys_recvfrom net/socket.c:2283 [inline]
__se_sys_recvfrom net/socket.c:2279 [inline]
__x64_sys_recvfrom+0xe0/0x1c0 net/socket.c:2279
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feb5d857559
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 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 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007feb5d7f1208 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
RAX: ffffffffffffffda RBX: 00007feb5d8e1318 RCX: 00007feb5d857559
RDX: 000000800000000e RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007feb5d8e1310 R08: 0000000000000000 R09: ffffffff81000000
R10: 0000000000000100 R11: 0000000000000246 R12: 00007feb5d8e131c
R13: 00007feb5d8ae074 R14: 000000800000000e R15: 00000000fffffdef
and provided a nice reproducer.
The root cause is the current bad handling of racing disconnect.
After the blamed commit below, sk_wait_data() can return (with
error) with the underlying socket disconnected and a zero rcv_mss.
Catch the error and return without performing any additional
operations on the current socket.
Reported-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Fixes: 419ce133ab92 ("tcp: allow again tcp_disconnect() when threads are waiting")
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Link: https://patch.msgid.link/8c82ecf71662ecbc47bf390f9905de70884c9f2d.1731060874.git.pabeni@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index d68e93dab88c3..78ac5c538e139 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2180,7 +2180,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
cmsg_flags = MPTCP_CMSG_INQ;
while (copied < len) {
- int bytes_read;
+ int err, bytes_read;
bytes_read = __mptcp_recvmsg_mskq(msk, msg, len - copied, flags, &tss, &cmsg_flags);
if (unlikely(bytes_read < 0)) {
@@ -2245,9 +2245,16 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
}
pr_debug("block timeout %ld\n", timeo);
- sk_wait_data(sk, &timeo, NULL);
+ mptcp_rcv_space_adjust(msk, copied);
+ err = sk_wait_data(sk, &timeo, NULL);
+ if (err < 0) {
+ err = copied ? : err;
+ goto out_err;
+ }
}
+ mptcp_rcv_space_adjust(msk, copied);
+
out_err:
if (cmsg_flags && copied >= 0) {
if (cmsg_flags & MPTCP_CMSG_TS)
@@ -2263,8 +2270,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
pr_debug("msk=%p rx queue empty=%d:%d copied=%d\n",
msk, skb_queue_empty_lockless(&sk->sk_receive_queue),
skb_queue_empty(&msk->receive_queue), copied);
- if (!(flags & MSG_PEEK))
- mptcp_rcv_space_adjust(msk, copied);
release_sock(sk);
return copied;
