[PATCH 4.19 113/243] altera-stapl: check for a null key before strcasecmping it

Greg Kroah-Hartman
2019-12-11T15:51:30Z

From: Colin Ian King <colin.king@canonical.com>

[ Upstream commit 9ccb645683ef46e3c52c12c088a368baa58447d4 ]

Currently the null check on key is occurring after the strcasecmp on
the key, hence there is a potential null pointer dereference on key.
Fix this by checking if key is null first. Also replace the == 0
check on strcasecmp with just the ! operator.

Detected by CoverityScan, CID#1248787 ("Dereference before null check")

Fixes: fa766c9be58b ("[media] Altera FPGA firmware download module")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/misc/altera-stapl/altera.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/misc/altera-stapl/altera.c b/drivers/misc/altera-stapl/altera.c
index ef83a9078646f..d2ed3b9728b7c 100644
--- a/drivers/misc/altera-stapl/altera.c
+++ b/drivers/misc/altera-stapl/altera.c
@@ -2176,8 +2176,7 @@ static int altera_get_note(u8 *p, s32 program_size,
key_ptr = &p[note_strings +
get_unaligned_be32(
&p[note_table + (8 * i)])];
- if ((strncasecmp(key, key_ptr, strlen(key_ptr)) == 0) &&
- (key != NULL)) {
+ if (key && !strncasecmp(key, key_ptr, strlen(key_ptr))) {
status = 0;

value_ptr = &p[note_strings +
--
2.20.1