From: Johannes Berg <johannes.berg@intel.com>
Date: Tue, 15 Dec 2020 09:52:22 +0000 (+0100)
Subject: um: virtio: fix handling of messages without payload
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=10c2b5aeb21c439251e5e828bf1362f89ab3de49;p=linux.git

um: virtio: fix handling of messages without payload

If we have a message without payload, we call full_read() with
len set to 0, which causes it to return -ECONNRESET. Catch this
case and explicitly return 0 for it so we can actually use the
zero-size config-changed message.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
---

diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index 515d648d3c3d3..ef620caed8e7b 100644
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -97,6 +97,9 @@ static int full_read(int fd, void *buf, int len, bool abortable)
 {
 	int rc;
 
+	if (!len)
+		return 0;
+
 	do {
 		rc = os_read_file(fd, buf, len);
 		if (rc > 0) {