linux-kernel - [PATCH v2] media: dvb_vb2: fix possible out of bound access

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Date:   Thu, 19 May 2022 10:17:43 +0800
From:   Hangyu Hua <hbh25y@...il.com>
To:     mchehab@...nel.org, senozhatsky@...omium.org,
        cai.huoqing@...ux.dev, hverkuil-cisco@...all.nl,
        sw0312.kim@...sung.com, satendra.t@...sung.com,
        jh1009.sung@...sung.com, nenggun.kim@...sung.com
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hangyu Hua <hbh25y@...il.com>
Subject: [PATCH v2] 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: 57868acc369a ("media: videobuf2: Add new uAPI for DVB streaming I/O")
Signed-off-by: Hangyu Hua <hbh25y@...il.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---

v2: 
1. fix inappropriate use of dprintk.
2. add "fixes" tag

 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..909df82fed33 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(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,
-- 
2.25.1