media: mtk-jpeg: Fix use after free bug due to error path handling in mtk_jpeg_dec_device_run

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: 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.

References

• https://git.kernel.org/stable/c/43872f44eee6c6781fea1348b38885d8e78face9
• https://git.kernel.org/stable/c/1b1036c60a37a30caf6759a90fe5ecd06ec35590
• https://git.kernel.org/stable/c/9fec4db7fff54d9b0306a332bab31eac47eeb5f6
• https://git.kernel.org/stable/c/8254d54d00eb6cdb8367399c7f912eb8d354ecd7
• https://git.kernel.org/stable/c/6e2f37022f0fc0893da4d85a0500c9d547fffd4c
• https://git.kernel.org/stable/c/206c857dd17d4d026de85866f1b5f0969f2a109e