2022-03-25 19:08:14

by Hangyu Hua

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

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 <[email protected]>
---
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

2022-05-18 10:53:32

by Hans Verkuil

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

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 <[email protected]>
> ---
> 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,

2022-05-19 01:51:57

by Hangyu Hua

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

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 <[email protected]>
>> ---
>> 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,