From: David Howells Date: Thu, 15 Jun 2023 11:32:02 +0000 (+0100) Subject: kcm: Fix unnecessary psock unreservation. X-Git-Tag: microblaze-v6.6~166^2~79 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=9f8d0dc0ec4a4b5b78c0be83238c4511ff5f1ae0;p=linux-2.6-microblaze.git kcm: Fix unnecessary psock unreservation. kcm_write_msgs() calls unreserve_psock() to release its hold on the underlying TCP socket if it has run out of things to transmit, but if we have nothing in the write queue on entry (e.g. because someone did a zero-length sendmsg), we don't actually go into the transmission loop and as a consequence don't call reserve_psock(). Fix this by skipping the call to unreserve_psock() if we didn't reserve a psock. Fixes: c31a25e1db48 ("kcm: Send multiple frags in one sendmsg()") Reported-by: syzbot+dd1339599f1840e4cc65@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/000000000000a61ffe05fe0c3d08@google.com/ Signed-off-by: David Howells Tested-by: syzbot+dd1339599f1840e4cc65@syzkaller.appspotmail.com cc: Tom Herbert cc: Tom Herbert cc: Jens Axboe cc: Matthew Wilcox Link: https://lore.kernel.org/r/20787.1686828722@warthog.procyon.org.uk Signed-off-by: Jakub Kicinski --- diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index d75d775e9462..d0537c1c8cd7 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -661,6 +661,7 @@ retry: kcm_abort_tx_psock(psock, ret ? -ret : EPIPE, true); unreserve_psock(kcm); + psock = NULL; txm->started_tx = false; kcm_report_tx_retry(kcm); @@ -696,7 +697,8 @@ out: if (!head) { /* Done with all queued messages. */ WARN_ON(!skb_queue_empty(&sk->sk_write_queue)); - unreserve_psock(kcm); + if (psock) + unreserve_psock(kcm); } /* Check if write space is available */