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.

Fixes: d0f97d6a4693 ("media: videobuf2: Add new uAPI for DVB streaming I/O")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

diff --git a/drivers/media/dvb-core/dvb_vb2.c b/drivers/media/dvb-core/dvb_vb2.c
index a1bd6d9c9223cdf9426b049da35127712c6b33cf..909df82fed3329f38fb73af0c3a3ac5c702566f2 100644 (file)
--- 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(1, "[%s] buffer index out of range\n", ctx->name);
+               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(1, "[%s] buffer index out of range\n", ctx->name);
+               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,