linux-kernel - [PATCH] media: vivid: fix compose size exceed boundary

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Date:   Thu, 27 Oct 2022 20:38:55 +0800
From:   Liu Shixin <liushixin2@...wei.com>
To:     Hans Verkuil <hverkuil@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
CC:     <linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Liu Shixin <liushixin2@...wei.com>
Subject: [PATCH] media: vivid: fix compose size exceed boundary

syzkaller found a bug:

 BUG: unable to handle page fault for address: ffffc9000a3b1000
 #PF: supervisor write access in kernel mode
 #PF: error_code(0x0002) - not-present page
 PGD 100000067 P4D 100000067 PUD 10015f067 PMD 1121ca067 PTE 0
 Oops: 0002 [#1] PREEMPT SMP
 CPU: 0 PID: 23489 Comm: vivid-000-vid-c Not tainted 6.1.0-rc1+ #512
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
 RIP: 0010:memcpy_erms+0x6/0x10
[...]
 Call Trace:
  <TASK>
  ? tpg_fill_plane_buffer+0x856/0x15b0
  vivid_fillbuff+0x8ac/0x1110
  vivid_thread_vid_cap_tick+0x361/0xc90
  vivid_thread_vid_cap+0x21a/0x3a0
  kthread+0x143/0x180
  ret_from_fork+0x1f/0x30
  </TASK>

This is because we forget to check boundary after adjust compose->height
int V4L2_SEL_TGT_CROP case. Add v4l2_rect_map_inside() to fix this problem
for this case.

Fixes: ef834f7836ec ("vivid: add the video capture and output parts")
Signed-off-by: Liu Shixin <liushixin2@...wei.com>
---
 drivers/media/test-drivers/vivid/vivid-vid-cap.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/media/test-drivers/vivid/vivid-vid-cap.c b/drivers/media/test-drivers/vivid/vivid-vid-cap.c
index 86b158eeb2d8..b0cee26b9089 100644
--- a/drivers/media/test-drivers/vivid/vivid-vid-cap.c
+++ b/drivers/media/test-drivers/vivid/vivid-vid-cap.c
@@ -957,6 +957,7 @@ int vivid_vid_cap_s_selection(struct file *file, void *fh, struct v4l2_selection
 			if (dev->has_compose_cap) {
 				v4l2_rect_set_min_size(compose, &min_rect);
 				v4l2_rect_set_max_size(compose, &max_rect);
+				v4l2_rect_map_inside(compose, &fmt);
 			}
 			dev->fmt_cap_rect = fmt;
 			tpg_s_buf_height(&dev->tpg, fmt.height);
-- 
2.25.1