[PATCH 5.15 265/317] RDMA/rtrs-clt: Check strnlen return len in sysfs mpath_policy_store()

[Sasha Levin]

From: Alexey Kodanev <aleksei.kodanev@xxxxxxxxxxx>

[ Upstream commit 7a7b7f575a25aa68ee934ee8107294487efcb3fe ]

strnlen() may return 0 (e.g. for "\0\n" string), it's better to
check the result of strnlen() before using 'len - 1' expression
for the 'buf' array index.

Detected using the static analysis tool - Svace.

Fixes: dc3b66a0ce70 ("RDMA/rtrs-clt: Add a minimum latency multipath policy")
Signed-off-by: Alexey Kodanev <aleksei.kodanev@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240221113204.147478-1-aleksei.kodanev@xxxxxxxxxxx
Acked-by: Jack Wang <jinpu.wang@xxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c b/drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c
index dbf9a778c3bd7..583c38eb04326 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c
@@ -131,7 +131,7 @@ static ssize_t mpath_policy_store(struct device *dev,
 
 	/* distinguish "mi" and "min-latency" with length */
 	len = strnlen(buf, NAME_MAX);
-	if (buf[len - 1] == '\n')
+	if (len && buf[len - 1] == '\n')
 		len--;
 
 	if (!strncasecmp(buf, "round-robin", 11) ||
-- 
2.43.0