在 2022/3/1 12:02, John Fastabend 写道:
Wang Yufen wrote:
If tcp_bpf_sendmsg() is running while sk msg is full, sk_msg_alloc()
returns -ENOSPC, tcp_bpf_sendmsg() goto wait for memory. If partial memory
has been alloced by sk_msg_alloc(), that is, msg_tx->sg.size is greater
than osize after sk_msg_alloc(), memleak occurs. To fix we use
sk_msg_trim() to release the allocated memory, then goto wait for memory.
Small nit, "sk_msg_alloc() returns -ENOSPC" should be something like, "when
sk_msg_alloc() returns -ENOMEM error,..." That error path is from ENOMEM not
the ENOSPC.
Thanks, I will fix in v2.
But nice find thanks! I think we might have seen this in a couple cases on
our side as well.
This issue can cause the following info:
WARNING: CPU: 3 PID: 7950 at net/core/stream.c:208 sk_stream_kill_queues+0xd4/0x1a0
Call Trace:
<TASK>
inet_csk_destroy_sock+0x55/0x110
__tcp_close+0x279/0x470
tcp_close+0x1f/0x60
inet_release+0x3f/0x80
__sock_release+0x3d/0xb0
sock_close+0x11/0x20
__fput+0x92/0x250
task_work_run+0x6a/0xa0
do_exit+0x33b/0xb60
do_group_exit+0x2f/0xa0
get_signal+0xb6/0x950
arch_do_signal_or_restart+0xac/0x2a0
exit_to_user_mode_prepare+0xa9/0x200
syscall_exit_to_user_mode+0x12/0x30
do_syscall_64+0x46/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
</TASK>
WARNING: CPU: 3 PID: 2094 at net/ipv4/af_inet.c:155 inet_sock_destruct+0x13c/0x260
Call Trace:
<TASK>
__sk_destruct+0x24/0x1f0
sk_psock_destroy+0x19b/0x1c0
process_one_work+0x1b3/0x3c0
kthread+0xe6/0x110
ret_from_fork+0x22/0x30
</TASK>
Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Wang Yufen <wangyufen@xxxxxxxxxx>
---
net/ipv4/tcp_bpf.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 9b9b02052fd3..ac9f491cc139 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -421,8 +421,10 @@ static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
osize = msg_tx->sg.size;
err = sk_msg_alloc(sk, msg_tx, msg_tx->sg.size + copy, msg_tx->sg.end - 1);
if (err) {
- if (err != -ENOSPC)
+ if (err != -ENOSPC) {
+ sk_msg_trim(sk, msg_tx, osize);
goto wait_for_memory;
+ }
enospc = true;
copy = msg_tx->sg.size - osize;
}
--
2.25.1
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
.
