[PATCH] media: dvb_vb2: fix possible out of bound access

[PATCH] media: dvb_vb2: fix possible out of bound access

[Hangyu Hua]

vb2_core_qbuf and vb2_core_querybuf don't check the range of b->index
controlled by the user.

Fix this by adding range checking code before using them.

Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
---
 drivers/media/dvb-core/dvb_vb2.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/media/dvb-core/dvb_vb2.c b/drivers/media/dvb-core/dvb_vb2.c
index a1bd6d9c9223..f410800b92e7 100644
--- a/drivers/media/dvb-core/dvb_vb2.c
+++ b/drivers/media/dvb-core/dvb_vb2.c
@@ -354,6 +354,12 @@ int dvb_vb2_reqbufs(struct dvb_vb2_ctx *ctx, struct dmx_requestbuffers *req)
 
 int dvb_vb2_querybuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer *b)
 {
+	struct vb2_queue *q = &ctx->vb_q;
+
+	if (b->index >= q->num_buffers) {
+		dprintk(q, 1, "buffer index out of range\n");
+		return -EINVAL;
+	}
 	vb2_core_querybuf(&ctx->vb_q, b->index, b);
 	dprintk(3, "[%s] index=%d\n", ctx->name, b->index);
 	return 0;
@@ -378,8 +384,13 @@ int dvb_vb2_expbuf(struct dvb_vb2_ctx *ctx, struct dmx_exportbuffer *exp)
 
 int dvb_vb2_qbuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer *b)
 {
+	struct vb2_queue *q = &ctx->vb_q;
 	int ret;
 
+	if (b->index >= q->num_buffers) {
+		dprintk(q, 1, "buffer index out of range\n");
+		return -EINVAL;
+	}
 	ret = vb2_core_qbuf(&ctx->vb_q, b->index, b, NULL);
 	if (ret) {
 		dprintk(1, "[%s] index=%d errno=%d\n", ctx->name,
-- 
2.25.1

Re: [PATCH] media: dvb_vb2: fix possible out of bound access

[Sergey Senozhatsky]

On (22/03/24 16:01), Hangyu Hua wrote:
> vb2_core_qbuf and vb2_core_querybuf don't check the range of b->index
> controlled by the user.
> 
> Fix this by adding range checking code before using them.
> 
> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>

Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>

Re: [PATCH] media: dvb_vb2: fix possible out of bound access

[Hangyu Hua]

On 2022/3/24 18:23, Sergey Senozhatsky wrote:
> On (22/03/24 16:01), Hangyu Hua wrote:
>> vb2_core_qbuf and vb2_core_querybuf don't check the range of b->index
>> controlled by the user.
>>
>> Fix this by adding range checking code before using them.
>>
>> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
> 
> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>

Hi guys,

Two other patches for this module that I submitted at the same time as 
this one have been accepted. But this bug looks much worse than the 
other two. Is this patch forgotten to merge?

Thanks.

Re: [PATCH] media: dvb_vb2: fix possible out of bound access

[Hans Verkuil]

Hi Hangyu,

It appears this patch fell through the cracks. It's certainly useful to
have.

On 3/24/22 09:01, Hangyu Hua wrote:
> vb2_core_qbuf and vb2_core_querybuf don't check the range of b->index
> controlled by the user.
> 
> Fix this by adding range checking code before using them.
> 
> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
> ---
>  drivers/media/dvb-core/dvb_vb2.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/media/dvb-core/dvb_vb2.c b/drivers/media/dvb-core/dvb_vb2.c
> index a1bd6d9c9223..f410800b92e7 100644
> --- a/drivers/media/dvb-core/dvb_vb2.c
> +++ b/drivers/media/dvb-core/dvb_vb2.c
> @@ -354,6 +354,12 @@ int dvb_vb2_reqbufs(struct dvb_vb2_ctx *ctx, struct dmx_requestbuffers *req)
>  
>  int dvb_vb2_querybuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer *b)
>  {
> +	struct vb2_queue *q = &ctx->vb_q;
> +
> +	if (b->index >= q->num_buffers) {
> +		dprintk(q, 1, "buffer index out of range\n");

However, this patch doesn't compile: dprintk in this source doesn't
have a 'q' argument!

> +		return -EINVAL;
> +	}
>  	vb2_core_querybuf(&ctx->vb_q, b->index, b);
>  	dprintk(3, "[%s] index=%d\n", ctx->name, b->index);

Also, to help debugging it prefixes the warnings with the ctx-name.

Can you post a v2 of this patch?

Regards,

	Hans

>  	return 0;
> @@ -378,8 +384,13 @@ int dvb_vb2_expbuf(struct dvb_vb2_ctx *ctx, struct dmx_exportbuffer *exp)
>  
>  int dvb_vb2_qbuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer *b)
>  {
> +	struct vb2_queue *q = &ctx->vb_q;
>  	int ret;
>  
> +	if (b->index >= q->num_buffers) {
> +		dprintk(q, 1, "buffer index out of range\n");
> +		return -EINVAL;
> +	}
>  	ret = vb2_core_qbuf(&ctx->vb_q, b->index, b, NULL);
>  	if (ret) {
>  		dprintk(1, "[%s] index=%d errno=%d\n", ctx->name,

Re: [PATCH] media: dvb_vb2: fix possible out of bound access

[Hangyu Hua]

On 2022/5/18 18:44, Hans Verkuil wrote:
> Hi Hangyu,
> 
> It appears this patch fell through the cracks. It's certainly useful to
> have.
> 
> On 3/24/22 09:01, Hangyu Hua wrote:
>> vb2_core_qbuf and vb2_core_querybuf don't check the range of b->index
>> controlled by the user.
>>
>> Fix this by adding range checking code before using them.
>>
>> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
>> ---
>>   drivers/media/dvb-core/dvb_vb2.c | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/media/dvb-core/dvb_vb2.c b/drivers/media/dvb-core/dvb_vb2.c
>> index a1bd6d9c9223..f410800b92e7 100644
>> --- a/drivers/media/dvb-core/dvb_vb2.c
>> +++ b/drivers/media/dvb-core/dvb_vb2.c
>> @@ -354,6 +354,12 @@ int dvb_vb2_reqbufs(struct dvb_vb2_ctx *ctx, struct dmx_requestbuffers *req)
>>   
>>   int dvb_vb2_querybuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer *b)
>>   {
>> +	struct vb2_queue *q = &ctx->vb_q;
>> +
>> +	if (b->index >= q->num_buffers) {
>> +		dprintk(q, 1, "buffer index out of range\n");
> 
> However, this patch doesn't compile: dprintk in this source doesn't
> have a 'q' argument!

Oops, i will fix this out.

> 
>> +		return -EINVAL;
>> +	}
>>   	vb2_core_querybuf(&ctx->vb_q, b->index, b);
>>   	dprintk(3, "[%s] index=%d\n", ctx->name, b->index);
> 
> Also, to help debugging it prefixes the warnings with the ctx-name.
> 
> Can you post a v2 of this patch?
> 
> Regards,
> 
> 	Hans

I will send a v2 later.

Thanks,
Hangyu

> 
>>   	return 0;
>> @@ -378,8 +384,13 @@ int dvb_vb2_expbuf(struct dvb_vb2_ctx *ctx, struct dmx_exportbuffer *exp)
>>   
>>   int dvb_vb2_qbuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer *b)
>>   {
>> +	struct vb2_queue *q = &ctx->vb_q;
>>   	int ret;
>>   
>> +	if (b->index >= q->num_buffers) {
>> +		dprintk(q, 1, "buffer index out of range\n");
>> +		return -EINVAL;
>> +	}
>>   	ret = vb2_core_qbuf(&ctx->vb_q, b->index, b, NULL);
>>   	if (ret) {
>>   		dprintk(1, "[%s] index=%d errno=%d\n", ctx->name,