RE: [PATCH 1/2] sctp: socket: Fix uninitialized error on socket shutdown

[Jagielski, Jedrzej]

From: luoqing <l1138897701@xxxxxxx> 
Sent: Thursday, July 16, 2026 8:53 AM

>From: luoqing <luoqing@xxxxxxxxxx>
>
>When sctp_skb_recv_datagram() detects sk->sk_shutdown & RCV_SHUTDOWN,
>it breaks out of the loop and returns NULL without setting *err.
>This leaves the error pointer uninitialized or with a stale value,
>which can confuse callers expecting a clean shutdown indication.
>
>Compare with the generic __skb_wait_for_more_packets() in
>net/core/datagram.c which properly handles shutdown by setting *err = 0.
>
>Fix this by setting *err = 0 before breaking when the socket is shut down,
>indicating an orderly shutdown rather than an error condition.

Hi luoqing

patch title should contain target tree
fix patches should contain 'fixes' tag and be targeted to net tree
please put Name + Surname for the signed-off-by tag

>
>Signed-off-by: luoqing <luoqing@xxxxxxxxxx>
>---
> net/sctp/socket.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
>diff --git a/net/sctp/socket.c b/net/sctp/socket.c
>index c7b9e325ec1c..ea7050b27715 100644
>--- a/net/sctp/socket.c
>+++ b/net/sctp/socket.c
>@@ -9117,8 +9117,10 @@ struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags, int *err)
> 		if (error)
> 			goto no_packet;
> 
>-		if (sk->sk_shutdown & RCV_SHUTDOWN)
>+		if (sk->sk_shutdown & RCV_SHUTDOWN) {
>+			*err = 0;

from what i see any of the sctp_skb_recv_datagram() callers doesn't use
@err - so at this point that fix doesn't affect any code
i'm wondering if we could just drop @err

> 			break;
>+		}
> 
> 
> 		/* User doesn't want to wait.  */
>-- 
>2.25.1