linux-kernel - [PATCH v2] media:exynos4-is: Fix a use after free in isp_video

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Message-Id: <20210427060255.3318-1-lyl2019@mail.ustc.edu.cn>
Date:   Mon, 26 Apr 2021 23:02:55 -0700
From:   Lv Yunlong <lyl2019@...l.ustc.edu.cn>
To:     s.nawrocki@...sung.com, mchehab@...nel.org, krzk@...nel.org
Cc:     linux-media@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Subject: [PATCH v2] media:exynos4-is: Fix a use after free in isp_video_release

In isp_video_release, file->private_data is freed via
_vb2_fop_release()->v4l2_fh_release(). But the freed
file->private_data is still used in v4l2_fh_is_singular_file()
->v4l2_fh_is_singular(file->private_data), which is a use
after free bug.

My patch set file->private_data to NULL after _vb2_fop_release()
to avoid the use after free.

Fixes: 34947b8aebe3f ("[media] exynos4-is: Add the FIMC-IS ISP capture DMA driver")
Signed-off-by: Lv Yunlong <lyl2019@...l.ustc.edu.cn>
---
 drivers/media/platform/exynos4-is/fimc-isp-video.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/exynos4-is/fimc-isp-video.c b/drivers/media/platform/exynos4-is/fimc-isp-video.c
index 612b9872afc8..2e04589068b4 100644
--- a/drivers/media/platform/exynos4-is/fimc-isp-video.c
+++ b/drivers/media/platform/exynos4-is/fimc-isp-video.c
@@ -315,7 +315,8 @@ static int isp_video_release(struct file *file)
 	}
 
 	_vb2_fop_release(file, NULL);
-
+	file->private_data = NULL;
+
 	if (v4l2_fh_is_singular_file(file)) {
 		fimc_pipeline_call(&ivc->ve, close);
 
-- 
2.25.1