vcodec: mediatek: add check for NULL for vsi->frm_bufs[vsi->new_fb_idx].buf.fb in vp9_swap_frm_bufs

[PATCH] vcodec: mediatek: add check for NULL for vsi->frm_bufs[vsi->new_fb_idx].buf.fb in vp9_swap_frm_bufs

Posted by Anastasia Belova 2 years ago

If vsi->frm_bufs[vsi->new_fb_idx].buf.fb == NULL while cleaning
fb_free_list NULL-pointer is dereferenced.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: f77e89854b3e ("[media] vcodec: mediatek: Add Mediatek VP9 Video Decoder Driver")

Signed-off-by: Anastasia Belova <abelova@astralinux.ru>
---
 drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
index 70b8383f7c8e..b0679aaf6192 100644
--- a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
+++ b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
@@ -512,7 +512,7 @@ static void vp9_swap_frm_bufs(struct vdec_vp9_inst *inst)
 	 * clean fb_free_list
 	 */
 	if (vsi->frm_bufs[vsi->new_fb_idx].ref_cnt == 0) {
-		if (!vp9_is_sf_ref_fb(
+		if (vsi->frm_bufs[vsi->new_fb_idx].buf.fb != NULL && !vp9_is_sf_ref_fb(
 			inst, vsi->frm_bufs[vsi->new_fb_idx].buf.fb)) {
 			struct vdec_fb *fb;
 
-- 
2.30.2

Re: [PATCH] vcodec: mediatek: add check for NULL for vsi->frm_bufs[vsi->new_fb_idx].buf.fb in vp9_swap_frm_bufs

Posted by Nicolas Dufresne 2 years ago

Hi,

Le vendredi 28 octobre 2022 à 15:58 +0300, Anastasia Belova a écrit :
> If vsi->frm_bufs[vsi->new_fb_idx].buf.fb == NULL while cleaning
> fb_free_list NULL-pointer is dereferenced.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: f77e89854b3e ("[media] vcodec: mediatek: Add Mediatek VP9 Video Decoder Driver")
> 
> Signed-off-by: Anastasia Belova <abelova@astralinux.ru>
> ---
>  drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
> index 70b8383f7c8e..b0679aaf6192 100644
> --- a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
> @@ -512,7 +512,7 @@ static void vp9_swap_frm_bufs(struct vdec_vp9_inst *inst)
>  	 * clean fb_free_list
>  	 */
>  	if (vsi->frm_bufs[vsi->new_fb_idx].ref_cnt == 0) {
> -		if (!vp9_is_sf_ref_fb(
> +		if (vsi->frm_bufs[vsi->new_fb_idx].buf.fb != NULL && !vp9_is_sf_ref_fb(
>  			inst, vsi->frm_bufs[vsi->new_fb_idx].buf.fb)) {
>  			struct vdec_fb *fb;

Perhaps we could try and maintain some readability ? I'd suggest to move the
check into vp9_is_sf_ref_fb() as an early return.

Nicolas

Re: [PATCH] vcodec: mediatek: add check for NULL for vsi->frm_bufs[vsi->new_fb_idx].buf.fb in vp9_swap_frm_bufs

Posted by AngeloGioacchino Del Regno 2 years ago

Il 28/10/22 15:02, Nicolas Dufresne ha scritto:
> Hi,
> 
> Le vendredi 28 octobre 2022 à 15:58 +0300, Anastasia Belova a écrit :
>> If vsi->frm_bufs[vsi->new_fb_idx].buf.fb == NULL while cleaning
>> fb_free_list NULL-pointer is dereferenced.
>>
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>
>> Fixes: f77e89854b3e ("[media] vcodec: mediatek: Add Mediatek VP9 Video Decoder Driver")
>>
>> Signed-off-by: Anastasia Belova <abelova@astralinux.ru>
>> ---
>>   drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
>> index 70b8383f7c8e..b0679aaf6192 100644
>> --- a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
>> +++ b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
>> @@ -512,7 +512,7 @@ static void vp9_swap_frm_bufs(struct vdec_vp9_inst *inst)
>>   	 * clean fb_free_list
>>   	 */
>>   	if (vsi->frm_bufs[vsi->new_fb_idx].ref_cnt == 0) {
>> -		if (!vp9_is_sf_ref_fb(
>> +		if (vsi->frm_bufs[vsi->new_fb_idx].buf.fb != NULL && !vp9_is_sf_ref_fb(
>>   			inst, vsi->frm_bufs[vsi->new_fb_idx].buf.fb)) {
>>   			struct vdec_fb *fb;
> 
> Perhaps we could try and maintain some readability ? I'd suggest to move the
> check into vp9_is_sf_ref_fb() as an early return.
> 

I don't think that this will ever happen, as the check was omitted because of being
totally sure that vsi->frm_bufs[vsi->new_fb_idx].buf.fb is not NULL.

In any case, it doesn't really cost anything to add a check... in which case, I
agree with Nicolas about moving that to vp9_is_sf_ref_fb().

	if (!fb)
		return false
	for .....

Regards,
Angelo