6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Shigeru Yoshida syoshida@redhat.com
[ Upstream commit cac23b7d7627915d967ce25436d7aae26e88ed06 ]
The following NULL pointer dereference issue occurred:
BUG: kernel NULL pointer dereference, address: 0000000000000000 <...> RIP: 0010:ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline] RIP: 0010:dccp_write_xmit+0x49/0x140 net/dccp/output.c:356 <...> Call Trace: <TASK> dccp_sendmsg+0x642/0x7e0 net/dccp/proto.c:801 inet_sendmsg+0x63/0x90 net/ipv4/af_inet.c:846 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x83/0xe0 net/socket.c:745 ____sys_sendmsg+0x443/0x510 net/socket.c:2558 ___sys_sendmsg+0xe5/0x150 net/socket.c:2612 __sys_sendmsg+0xa6/0x120 net/socket.c:2641 __do_sys_sendmsg net/socket.c:2650 [inline] __se_sys_sendmsg net/socket.c:2648 [inline] __x64_sys_sendmsg+0x45/0x50 net/socket.c:2648 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x43/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b
sk_wait_event() returns an error (-EPIPE) if disconnect() is called on the socket waiting for the event. However, sk_stream_wait_connect() returns success, i.e. zero, even if sk_wait_event() returns -EPIPE, so a function that waits for a connection with sk_stream_wait_connect() may misbehave.
In the case of the above DCCP issue, dccp_sendmsg() is waiting for the connection. If disconnect() is called in concurrently, the above issue occurs.
This patch fixes the issue by returning error from sk_stream_wait_connect() if sk_wait_event() fails.
Fixes: 419ce133ab92 ("tcp: allow again tcp_disconnect() when threads are waiting") Signed-off-by: Shigeru Yoshida syoshida@redhat.com Reviewed-by: Kuniyuki Iwashima kuniyu@amazon.com Reported-by: syzbot+c71bc336c5061153b502@syzkaller.appspotmail.com Reviewed-by: Eric Dumazet edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com Reported-by: syzkaller syzkaller@googlegroups.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/stream.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/stream.c b/net/core/stream.c index 051aa71a8ad0f..30e7deff4c551 100644 --- a/net/core/stream.c +++ b/net/core/stream.c @@ -79,7 +79,7 @@ int sk_stream_wait_connect(struct sock *sk, long *timeo_p) remove_wait_queue(sk_sleep(sk), &wait); sk->sk_write_pending--; } while (!done); - return 0; + return done < 0 ? done : 0; } EXPORT_SYMBOL(sk_stream_wait_connect);