From: Tiffany Lin <tiffany.lin@mediatek.com> To: Hans Verkuil <hverkuil@xs4all.nl> Cc: Dan Carpenter <dan.carpenter@oracle.com>, <linux-media@vger.kernel.org>, <linux-mediatek@lists.infradead.org> Subject: Re: [bug report] [media] vcodec: mediatek: Add Mediatek V4L2 Video Decoder Driver Date: Thu, 10 Nov 2016 12:31:30 +0800 [thread overview] Message-ID: <1478752290.2580.6.camel@mtksdaap41> (raw) In-Reply-To: <9794dab1-94ba-c384-85c5-edb8831810ff@xs4all.nl> Hi Hans, Dan, On Wed, 2016-11-09 at 14:45 +0100, Hans Verkuil wrote: > On 11/09/16 14:28, Dan Carpenter wrote: > > Hello Tiffany Lin, > > > > The patch 590577a4e525: "[media] vcodec: mediatek: Add Mediatek V4L2 > > Video Decoder Driver" from Sep 2, 2016, leads to the following static > > checker warning: > > > > drivers/media/platform/mtk-vcodec/mtk_vcodec_dec.c:536 vidioc_vdec_qbuf() > > error: buffer overflow 'vq->bufs' 32 <= u32max > > > > drivers/media/platform/mtk-vcodec/mtk_vcodec_dec.c > > 520 static int vidioc_vdec_qbuf(struct file *file, void *priv, > > 521 struct v4l2_buffer *buf) > > 522 { > > 523 struct mtk_vcodec_ctx *ctx = fh_to_ctx(priv); > > 524 struct vb2_queue *vq; > > 525 struct vb2_buffer *vb; > > 526 struct mtk_video_dec_buf *mtkbuf; > > 527 struct vb2_v4l2_buffer *vb2_v4l2; > > 528 > > 529 if (ctx->state == MTK_STATE_ABORT) { > > 530 mtk_v4l2_err("[%d] Call on QBUF after unrecoverable error", > > 531 ctx->id); > > 532 return -EIO; > > 533 } > > 534 > > 535 vq = v4l2_m2m_get_vq(ctx->m2m_ctx, buf->type); > > 536 vb = vq->bufs[buf->index]; > > > > Smatch thinks that "buf->index" comes straight from the user without > > being checked and that this is a buffer overflow. It seems simple > > enough to analyse the call tree. > > > > __video_do_ioctl() > > -> v4l_qbuf() > > -> vidioc_vdec_qbuf() > > > > It seems like Smatch is correct. I looked at a different implementation > > of this and that one wasn't checked either so maybe there is something > > I am not seeing. > > > > This has obvious security implications. Can someone take a look at > > this? > > This is indeed wrong. > > The v4l2_m2m_qbuf() call at the end of this function calls in turn > vb2_qbuf which > will check the index. But if you override vidioc_qbuf (or > vidioc_prepare), then > you need to check the index value. > > I double-checked all cases where vidioc_qbuf was set to a > driver-specific function > and this is the only driver that doesn't check the index field. In all > other cases > it is either checked, or it is not used before calling into the vb1/vb2 > framework > which checks this. > > So luckily this only concerns this driver. Thanks for point out this issue. As Hans' mentioned, our driver access index field in v4l2_buffer before framework check buffer index. We will prepare patch for this issue. best regards, Tiffany > > Regards, > > Hans > > > > > 537 vb2_v4l2 = container_of(vb, struct vb2_v4l2_buffer, vb2_buf); > > 538 mtkbuf = container_of(vb2_v4l2, struct mtk_video_dec_buf, vb); > > 539 > > 540 if ((buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) && > > 541 (buf->m.planes[0].bytesused == 0)) { > > 542 mtkbuf->lastframe = true; > > 543 mtk_v4l2_debug(1, "[%d] (%d) id=%d lastframe=%d (%d,%d, %d) vb=%p", > > 544 ctx->id, buf->type, buf->index, > > 545 mtkbuf->lastframe, buf->bytesused, > > 546 buf->m.planes[0].bytesused, buf->length, > > 547 vb); > > 548 } > > 549 > > 550 return v4l2_m2m_qbuf(file, ctx->m2m_ctx, buf); > > 551 } > > > > regards, > > dan carpenter > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-media" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > >
WARNING: multiple messages have this Message-ID (diff)
From: Tiffany Lin <tiffany.lin@mediatek.com> To: Hans Verkuil <hverkuil@xs4all.nl> Cc: Dan Carpenter <dan.carpenter@oracle.com>, linux-media@vger.kernel.org, linux-mediatek@lists.infradead.org Subject: Re: [bug report] [media] vcodec: mediatek: Add Mediatek V4L2 Video Decoder Driver Date: Thu, 10 Nov 2016 12:31:30 +0800 [thread overview] Message-ID: <1478752290.2580.6.camel@mtksdaap41> (raw) In-Reply-To: <9794dab1-94ba-c384-85c5-edb8831810ff@xs4all.nl> Hi Hans, Dan, On Wed, 2016-11-09 at 14:45 +0100, Hans Verkuil wrote: > On 11/09/16 14:28, Dan Carpenter wrote: > > Hello Tiffany Lin, > > > > The patch 590577a4e525: "[media] vcodec: mediatek: Add Mediatek V4L2 > > Video Decoder Driver" from Sep 2, 2016, leads to the following static > > checker warning: > > > > drivers/media/platform/mtk-vcodec/mtk_vcodec_dec.c:536 vidioc_vdec_qbuf() > > error: buffer overflow 'vq->bufs' 32 <= u32max > > > > drivers/media/platform/mtk-vcodec/mtk_vcodec_dec.c > > 520 static int vidioc_vdec_qbuf(struct file *file, void *priv, > > 521 struct v4l2_buffer *buf) > > 522 { > > 523 struct mtk_vcodec_ctx *ctx = fh_to_ctx(priv); > > 524 struct vb2_queue *vq; > > 525 struct vb2_buffer *vb; > > 526 struct mtk_video_dec_buf *mtkbuf; > > 527 struct vb2_v4l2_buffer *vb2_v4l2; > > 528 > > 529 if (ctx->state == MTK_STATE_ABORT) { > > 530 mtk_v4l2_err("[%d] Call on QBUF after unrecoverable error", > > 531 ctx->id); > > 532 return -EIO; > > 533 } > > 534 > > 535 vq = v4l2_m2m_get_vq(ctx->m2m_ctx, buf->type); > > 536 vb = vq->bufs[buf->index]; > > > > Smatch thinks that "buf->index" comes straight from the user without > > being checked and that this is a buffer overflow. It seems simple > > enough to analyse the call tree. > > > > __video_do_ioctl() > > -> v4l_qbuf() > > -> vidioc_vdec_qbuf() > > > > It seems like Smatch is correct. I looked at a different implementation > > of this and that one wasn't checked either so maybe there is something > > I am not seeing. > > > > This has obvious security implications. Can someone take a look at > > this? > > This is indeed wrong. > > The v4l2_m2m_qbuf() call at the end of this function calls in turn > vb2_qbuf which > will check the index. But if you override vidioc_qbuf (or > vidioc_prepare), then > you need to check the index value. > > I double-checked all cases where vidioc_qbuf was set to a > driver-specific function > and this is the only driver that doesn't check the index field. In all > other cases > it is either checked, or it is not used before calling into the vb1/vb2 > framework > which checks this. > > So luckily this only concerns this driver. Thanks for point out this issue. As Hans' mentioned, our driver access index field in v4l2_buffer before framework check buffer index. We will prepare patch for this issue. best regards, Tiffany > > Regards, > > Hans > > > > > 537 vb2_v4l2 = container_of(vb, struct vb2_v4l2_buffer, vb2_buf); > > 538 mtkbuf = container_of(vb2_v4l2, struct mtk_video_dec_buf, vb); > > 539 > > 540 if ((buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) && > > 541 (buf->m.planes[0].bytesused == 0)) { > > 542 mtkbuf->lastframe = true; > > 543 mtk_v4l2_debug(1, "[%d] (%d) id=%d lastframe=%d (%d,%d, %d) vb=%p", > > 544 ctx->id, buf->type, buf->index, > > 545 mtkbuf->lastframe, buf->bytesused, > > 546 buf->m.planes[0].bytesused, buf->length, > > 547 vb); > > 548 } > > 549 > > 550 return v4l2_m2m_qbuf(file, ctx->m2m_ctx, buf); > > 551 } > > > > regards, > > dan carpenter > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-media" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > >
next prev parent reply other threads:[~2016-11-10 4:31 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-11-09 13:28 [bug report] [media] vcodec: mediatek: Add Mediatek V4L2 Video Decoder Driver Dan Carpenter 2016-11-09 13:28 ` Dan Carpenter 2016-11-09 13:45 ` Hans Verkuil 2016-11-10 4:31 ` Tiffany Lin [this message] 2016-11-10 4:31 ` Tiffany Lin 2016-11-10 13:30 ` Dan Carpenter
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