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kcm: Fix error handling for SOCK_DGRAM in kcm_sendmsg().
[ Upstream commita22730b1b4
] syzkaller found a memory leak in kcm_sendmsg(), and commitc821a88bd7
("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> Signed-off-by: Sasha Levin <sashal@kernel.org>
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parent
5e93c6044b
commit
992b2ac783
1 changed files with 8 additions and 7 deletions
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@ -930,17 +930,18 @@ static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
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out_error:
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kcm_push(kcm);
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if (copied && sock->type == SOCK_SEQPACKET) {
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if (sock->type == SOCK_SEQPACKET) {
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/* Wrote some bytes before encountering an
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* error, return partial success.
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*/
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goto partial_message;
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}
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if (head != kcm->seq_skb)
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if (copied)
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goto partial_message;
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if (head != kcm->seq_skb)
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kfree_skb(head);
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} else {
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kfree_skb(head);
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else if (copied)
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kcm_tx_msg(head)->last_skb = skb;
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kcm->seq_skb = NULL;
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}
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err = sk_stream_error(sk, msg->msg_flags, err);
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