Kernel/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-12-29 17:25:38 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

kcm: Fix error handling for SOCK_DGRAM in kcm_sendmsg().

Browse Source 
syzkaller found a memory leak in kcm_sendmsg(), and commit c821a88bd7
("kcm: Fix memory leak in error path of kcm_sendmsg()") suppressed it by
updating kcm_tx_msg(head)->last_skb if partial data is copied so that the
following sendmsg() will resume from the skb.

However, we cannot know how many bytes were copied when we get the error.
Thus, we could mess up the MSG_MORE queue.

When kcm_sendmsg() fails for SOCK_DGRAM, we should purge the queue as we
do so for UDP by udp_flush_pending_frames().

Even without this change, when the error occurred, the following sendmsg()
resumed from a wrong skb and the queue was messed up.  However, we have
yet to get such a report, and only syzkaller stumbled on it.  So, this
can be changed safely.

Note this does not change SOCK_SEQPACKET behaviour.

Fixes: c821a88bd7 ("kcm: Fix memory leak in error path of kcm_sendmsg()")
Fixes: ab7ac4eb98 ("kcm: Kernel Connection Multiplexor module")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230912022753.33327-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Kuniyuki Iwashima 2023-09-11 19:27:53 -07:00 committed by Paolo Abeni
parent 96f7dc6934
commit a22730b1b4
1 changed files with 8 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
net/kcm/kcmsock.c
View File

@ -930,17 +930,18 @@ static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
out_error:
kcm_push(kcm);
if (copied && sock->type == SOCK_SEQPACKET) {
if (sock->type == SOCK_SEQPACKET) {
/* Wrote some bytes before encountering an
* error, return partial success.
*/
goto partial_message;
}
if (head != kcm->seq_skb)
if (copied)
goto partial_message;
if (head != kcm->seq_skb)
kfree_skb(head);
} else {
kfree_skb(head);
else if (copied)
kcm_tx_msg(head)->last_skb = skb;
kcm->seq_skb = NULL;
}
err = sk_stream_error(sk, msg->msg_flags, err);