commit 9633ab52460f58c92c6daa35e9d24e4ce9c5ab1c

Author: Miroslav Lichvar <mlichvar@redhat.com>

Date:   Tue Feb 23 11:01:43 2021 +0100

    sk: Don't return error for zero-length messages.

    The recvmsg() call can return zero for a zero-length UDP message, which

    should be handled as a bad message and not a fault of the port. This was

    addressed in commit 6b61ba29c78e ("Avoid fault when receiving zero

    length packets"), but later regressed in commit a6e0b83bd503

    ("sk: Convey transmit path errors to the caller.").

    Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>

    Fixes: a6e0b83bd503 ("sk: Convey transmit path errors to the caller.")

diff --git a/sk.c b/sk.c

index c9ef4d2..8be0708 100644

--- a/sk.c

+++ b/sk.c

@@ -391,7 +391,7 @@ int sk_receive(int fd, void *buf, int buflen,

 	if (!ts) {

 		memset(&hwts->ts, 0, sizeof(hwts->ts));

-		return cnt < 1 ? -errno : cnt;

+		return cnt < 0 ? -errno : cnt;

 	}

 	switch (hwts->type) {

@@ -407,7 +407,7 @@ int sk_receive(int fd, void *buf, int buflen,

 		hwts->ts = timespec_to_tmv(ts[1]);

 		break;

 	}

-	return cnt < 1 ? -errno : cnt;

+	return cnt < 0 ? -errno : cnt;

 }

 int sk_set_priority(int fd, int family, uint8_t dscp)