Virtualization - Feb 2019 - [PATCH net V2] vhost: correctly check the return value of translate_desc() in log_used()

When fail, translate_desc() returns negative value, otherwise the
number of iovs. So we should fail when the return value is negative
instead of a blindly check against zero.

Detected by CoverityScan, CID# 1442593:  Control flow issues  (DEADCODE)

Fixes: cc5e71075947 ("vhost: log dirty page correctly")
Acked-by: Michael S. Tsirkin <mst at redhat.com>
Reported-by: Stephen Hemminger <stephen at networkplumber.org>
Signed-off-by: Jason Wang <jasowang at redhat.com>
---
 drivers/vhost/vhost.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 24a129fcdd61..a2e5dc7716e2 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1788,7 +1788,7 @@ static int log_used(struct vhost_virtqueue *vq, u64
used_offset, u64 len)
 
 	ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
 			     len, iov, 64, VHOST_ACCESS_WO);
-	if (ret)
+	if (ret < 0)
 		return ret;
 
 	for (i = 0; i < ret; i++) {
-- 
2.17.1

From: Jason Wang <jasowang at redhat.com>
Date: Tue, 19 Feb 2019 14:53:44 +0800
> When fail, translate_desc() returns negative value, otherwise the
> number of iovs. So we should fail when the return value is negative
> instead of a blindly check against zero.
> 
> Detected by CoverityScan, CID# 1442593:  Control flow issues  (DEADCODE)
> 
> Fixes: cc5e71075947 ("vhost: log dirty page correctly")
> Acked-by: Michael S. Tsirkin <mst at redhat.com>
> Reported-by: Stephen Hemminger <stephen at networkplumber.org>
> Signed-off-by: Jason Wang <jasowang at redhat.com>
Applied and queued up for -stable, thanks.