2020-07-22 13:11:05

by Colin King

Subject: [PATCH][next][V2] media: allegro: fix potential null dereference on header

From: Colin Ian King <[email protected]>

The pointer header is an alias to msg and msg is being null checked.
However, if msg is null then header is also null and this can lead to
a null pointer dereference on the assignment type = header->type. Fix
this just using header->type after the null check and removing the need
for type as it is only used once.

Addresses-Coverity: ("Dereference before null check")
Fixes: 3de16839669f ("media: allegro: add explicit mail encoding and decoding")
Signed-off-by: Colin Ian King <[email protected]>
---

V2: remove need for variable type, as suggested by Michael Tretter

---
drivers/staging/media/allegro-dvt/allegro-mail.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/staging/media/allegro-dvt/allegro-mail.c b/drivers/staging/media/allegro-dvt/allegro-mail.c
index 4ac65de12463..9286d2162377 100644
--- a/drivers/staging/media/allegro-dvt/allegro-mail.c
+++ b/drivers/staging/media/allegro-dvt/allegro-mail.c
@@ -462,13 +462,12 @@ allegro_dec_encode_frame(struct mcu_msg_encode_frame_response *msg, u32 *src)
ssize_t allegro_encode_mail(u32 *dst, void *msg)
{
const struct mcu_msg_header *header = msg;
- enum mcu_msg_type type = header->type;
ssize_t size;

if (!msg || !dst)
return -EINVAL;

- switch (type) {
+ switch (header->type) {
case MCU_MSG_TYPE_INIT:
size = allegro_enc_init(&dst[1], msg);
break;
--
2.27.0

2020-07-22 13:17:19

by Michael Tretter

Subject: Re: [PATCH][next][V2] media: allegro: fix potential null dereference on header

On Wed, 22 Jul 2020 14:09:03 +0100, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> The pointer header is an alias to msg and msg is being null checked.
> However, if msg is null then header is also null and this can lead to
> a null pointer dereference on the assignment type = header->type. Fix
> this just using header->type after the null check and removing the need
> for type as it is only used once.
>
> Addresses-Coverity: ("Dereference before null check")
> Fixes: 3de16839669f ("media: allegro: add explicit mail encoding and decoding")
> Signed-off-by: Colin Ian King <[email protected]>

Reviewed-by: Michael Tretter <[email protected]>

> ---
>
> V2: remove need for variable type, as suggested by Michael Tretter
>
> ---
> drivers/staging/media/allegro-dvt/allegro-mail.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/staging/media/allegro-dvt/allegro-mail.c b/drivers/staging/media/allegro-dvt/allegro-mail.c
> index 4ac65de12463..9286d2162377 100644
> --- a/drivers/staging/media/allegro-dvt/allegro-mail.c
> +++ b/drivers/staging/media/allegro-dvt/allegro-mail.c
> @@ -462,13 +462,12 @@ allegro_dec_encode_frame(struct mcu_msg_encode_frame_response *msg, u32 *src)
> ssize_t allegro_encode_mail(u32 *dst, void *msg)
> {
> const struct mcu_msg_header *header = msg;
> - enum mcu_msg_type type = header->type;
> ssize_t size;
>
> if (!msg || !dst)
> return -EINVAL;
>
> - switch (type) {
> + switch (header->type) {
> case MCU_MSG_TYPE_INIT:
> size = allegro_enc_init(&dst[1], msg);
> break;
> --
> 2.27.0
>
>