linux/drivers/media/platform/mediatek/vcodec, branch master

media: mediatek: vcodec: fix use-after-free in encoder release path

2026-03-23T10:18:34Z

The fops_vcodec_release() function frees the context structure (ctx) without first cancelling any pending or running work in ctx->encode_work. This creates a race window where the workqueue handler (mtk_venc_worker) may still be accessing the context memory after it has been freed. Race condition: CPU 0 (release path) CPU 1 (workqueue) --------------------- ------------------ fops_vcodec_release() v4l2_m2m_ctx_release() v4l2_m2m_cancel_job() // waits for m2m job "done" mtk_venc_worker() v4l2_m2m_job_finish() // m2m job "done" // BUT worker still running! // post-job_finish access: other ctx dereferences // UAF if ctx already freed // returns (job "done") kfree(ctx) // ctx freed Root cause: The v4l2_m2m_ctx_release() only waits for the m2m job lifecycle (via TRANS_RUNNING flag), not the workqueue lifecycle. After v4l2_m2m_job_finish() is called, the m2m framework considers the job complete and v4l2_m2m_ctx_release() returns, but the worker function continues executing and may still access ctx. The work is queued during encode operations via: queue_work(ctx->dev->encode_workqueue, &ctx->encode_work) The worker function accesses ctx->m2m_ctx, ctx->dev, and other ctx fields even after calling v4l2_m2m_job_finish(). This vulnerability was confirmed with KASAN by running an instrumented test module that widens the post-job_finish race window. KASAN detected: BUG: KASAN: slab-use-after-free in mtk_venc_worker+0x159/0x180 Read of size 4 at addr ffff88800326e000 by task kworker/u8:0/12 Workqueue: mtk_vcodec_enc_wq mtk_venc_worker Allocated by task 47: __kasan_kmalloc+0x7f/0x90 fops_vcodec_open+0x85/0x1a0 Freed by task 47: __kasan_slab_free+0x43/0x70 kfree+0xee/0x3a0 fops_vcodec_release+0xb7/0x190 Fix this by calling cancel_work_sync(&ctx->encode_work) before kfree(ctx). This ensures the workqueue handler is both cancelled (if pending) and synchronized (waits for any running handler to complete) before the context is freed. Placement rationale: The fix is placed after v4l2_ctrl_handler_free() and before list_del_init(&ctx->list). At this point, all m2m operations are done (v4l2_m2m_ctx_release() has returned), and we need to ensure the workqueue is synchronized before removing ctx from the list and freeing it. Note: The open error path does NOT need cancel_work_sync() because INIT_WORK() only initializes the work structure - it does not schedule it. Work is only scheduled later during device_run() operations. Fixes: 0934d3759615 ("media: mediatek: vcodec: separate decoder and encoder") Cc: stable@vger.kernel.org Signed-off-by: Fan Wu Reviewed-by: Nicolas Dufresne Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51Z

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28Z

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

media: mediatek: vcodec: Discard pm_runtime_put() return value

2026-01-13T08:41:59Z

Printing error messages on pm_runtime_put() returning negative values is not particularly useful. Returning an error code from pm_runtime_put() merely means that it has not queued up a work item to check whether or not the device can be suspended and there are many perfectly valid situations in which that can happen, like after writing "on" to the devices' runtime PM "control" attribute in sysfs for one example. Accordingly, update mtk_vcodec_enc_pw_off() and mtk_vcodec_dec_pw_off() to simply discard the return value of pm_runtime_put(). This will facilitate a planned change of the pm_runtime_put() return type to void in the future. Signed-off-by: Rafael J. Wysocki Reviewed-by: Nicolas Dufresne Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil

media: mediatek: vcodec: Don't try to decode 422/444 VP9

2026-01-05T14:56:31Z

This is not supported by the hardware and trying to decode these leads to LAT timeout errors. Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil

media: mediatek: vcodec: Implement manual request completion

2026-01-05T14:56:31Z

Rework how requests are completed in the MediaTek VCodec driver, by implementing the new manual request completion feature, which allows to keep a request open while allowing to add new bitstream data. This is useful in this case, because the hardware has a LAT and a core decode work, after the LAT decode the bitstream isn't required anymore so the source buffer can be set done and the request stays open until the core decode work finishes. Signed-off-by: Sebastian Fricke Co-developed-by: Nicolas Dufresne Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil

media: mediatek: vcodec: use = { } instead of memset()

2026-01-05T14:56:31Z

Based on testing and recommendations by David Lechner et al. [1][2], using = { } to initialize a structure or array is the preferred way to do this in the kernel. Converts memset() to = { }, thereby: - Eliminating the risk of sizeof() mismatches. - Simplifying the code. [1]: https://lore.kernel.org/linux-iio/202505090942.48EBF01B@keescook/ [2]: https://lore.kernel.org/lkml/20250614151844.50524610@jic23-huawei/ Signed-off-by: Qianfeng Rong Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil

media: mediatek: encoder: Fix uninitialized scalar variable issue

2026-01-05T14:56:31Z

UNINIT checker finds some instances of variables that are used without being initialized, for example using the uninitialized value enc_result.is_key_frm can result in unpredictable behavior, so initialize these variables after declaring. Fixes: 4e855a6efa54 ("[media] vcodec: mediatek: Add Mediatek V4L2 Video Encoder Driver") Cc: stable@vger.kernel.org Signed-off-by: Irui Wang Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil

media: mediatek: vcodec: Fix a reference leak in mtk_vcodec_fw_vpu_init()

2025-10-20T07:23:17Z

vpu_get_plat_device() increases the reference count of the returned platform device. However, when devm_kzalloc() fails, the reference is not released, causing a reference leak. Fix this by calling put_device() on fw_pdev->dev before returning on the error path. Fixes: e25a89f743b1 ("media: mtk-vcodec: potential dereference of null pointer") Cc: stable@vger.kernel.org Signed-off-by: Haoxiang Li Reviewed-by: AngeloGioacchino Del Regno Reviewed-by: Tzung-Bi Shih Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil

media: mediatek: vcodec: Use spinlock for context list protection lock

2025-10-20T07:23:17Z

Previously a mutex was added to protect the encoder and decoder context lists from unexpected changes originating from the SCP IP block, causing the context pointer to go invalid, resulting in a NULL pointer dereference in the IPI handler. Turns out on the MT8173, the VPU IPI handler is called from hard IRQ context. This causes a big warning from the scheduler. This was first reported downstream on the ChromeOS kernels, but is also reproducible on mainline using Fluster with the FFmpeg v4l2m2m decoders. Even though the actual capture format is not supported, the affected code paths are triggered. Since this lock just protects the context list and operations on it are very fast, it should be OK to switch to a spinlock. Fixes: 6467cda18c9f ("media: mediatek: vcodec: adding lock to protect decoder context list") Fixes: afaaf3a0f647 ("media: mediatek: vcodec: adding lock to protect encoder context list") Cc: Yunfei Dong Cc: stable@vger.kernel.org Signed-off-by: Chen-Yu Tsai Reviewed-by: Fei Shao Reviewed-by: Tomasz Figa Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil