FAILED: patch "[PATCH] media: mtk-jpeg: Fix use after free bug due to error path" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 206c857dd17d4d026de85866f1b5f0969f2a109e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024012656-unaligned-conductor-4ef5@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

206c857dd17d ("media: mtk-jpeg: Fix use after free bug due to error path handling in mtk_jpeg_dec_device_run") 2023a9981111 ("media: platform: rename mediatek/mtk-jpeg/ to mediatek/jpeg/")
63fe3d27b226 ("media: platform/*/Kconfig: make manufacturer menus more uniform") f2ab6d3e8c48 ("media: platform: Create vendor/{Makefile,Kconfig} files")
8148baabd1c4 ("media: platform: re-structure TI drivers")
012e3ca3cb4d ("media: platform: rename omap/ to ti/omap/")
ceafdaac46ea ("media: platform: rename omap3isp/ to ti/omap3isp/")
d24a170bde65 ("media: platform: rename davinci/ to ti/davinci/")
407965e2348e ("media: platform: rename am437x/ to ti/am437x/")
e7b8153e2a4f ("media: platform: place stm32/ and sti/ under st/ dir")
43ecec16c4fa ("media: platform: rename s5p-mfc/ to samsung/s5p-mfc/")
f4104b7851a8 ("media: platform: rename s5p-jpeg/ to samsung/s5p-jpeg/")
a7f3b2d32dab ("media: platform: rename s5p-g2d/ to samsung/s5p-g2d/")
c1024049033f ("media: platform: rename s3c-camif/ to samsung/s3c-camif/")
3bae07d4b44c ("media: platform: rename exynos-gsc/ to samsung/exynos-gsc/")
238c84f71120 ("media: platform: rename exynos4-is/ to samsung/exynos4-is/")
9b18ef7c9ff4 ("media: platform: rename tegra/vde/ to nvidia/tegra-vde/")
574476a7d05d ("media: platform: rename mtk-vpu/ to mediatek/mtk-vpu/")
728dc4075acc ("media: platform: rename mtk-vcodec/ to mediatek/mtk-vcodec/")
1cb72963fa1e ("media: platform: rename mtk-mdp/ to mediatek/mtk-mdp/")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 206c857dd17d4d026de85866f1b5f0969f2a109e Mon Sep 17 00:00:00 2001
From: Zheng Wang <[email protected]>
Date: Mon, 6 Nov 2023 15:48:10 +0100
Subject: [PATCH] media: mtk-jpeg: Fix use after free bug due to error path
handling in mtk_jpeg_dec_device_run

In mtk_jpeg_probe, &jpeg->job_timeout_work is bound with mtk_jpeg_job_timeout_work.

In mtk_jpeg_dec_device_run, if error happens in mtk_jpeg_set_dec_dst, it will finally start the worker while mark the job as finished by invoking v4l2_m2m_job_finish.

There are two methods to trigger the bug. If we remove the module, it which will call mtk_jpeg_remove to make cleanup. The possible sequence is as follows, which will cause a use-after-free bug.

CPU0 CPU1
mtk_jpeg_dec_... |
start worker |

                    |mtk_jpeg_job_timeout_work
mtk_jpeg_remove     |
  v4l2_m2m_release  |
    kfree(m2m_dev); |
                    |
                    | v4l2_m2m_get_curr_priv
                    |   m2m_dev->curr_ctx //use

If we close the file descriptor, which will call mtk_jpeg_release, it will have a similar sequence.

Fix this bug by starting timeout worker only if started jpegdec worker successfully. Then v4l2_m2m_job_finish will only be called in either mtk_jpeg_job_timeout_work or mtk_jpeg_dec_device_run.

index 7c2e6a2f6c40..63165f05e123 100644
@@ -1020,13 +1020,13 @@ static void mtk_jpeg_dec_device_run(void *priv)
 	if (ret < 0)
 		goto dec_end;
 
-	schedule_delayed_work(&jpeg->job_timeout_work,
-			      msecs_to_jiffies(MTK_JPEG_HW_TIMEOUT_MSEC));
-
 	mtk_jpeg_set_dec_src(ctx, &src_buf->vb2_buf, &bs);
 	if (mtk_jpeg_set_dec_dst(ctx, &jpeg_src_buf->dec_param, &dst_buf->vb2_buf, &fb))
 		goto dec_end;
 
+	schedule_delayed_work(&jpeg->job_timeout_work,
+			      msecs_to_jiffies(MTK_JPEG_HW_TIMEOUT_MSEC));
+
 	spin_lock_irqsave(&jpeg->hw_lock, flags);
 	mtk_jpeg_dec_reset(jpeg->reg_base);
 	mtk_jpeg_dec_set_config(jpeg->reg_base,