From: Fan Wu Date: Wed, 4 Mar 2026 03:19:34 +0000 (+0000) Subject: media: mtk-jpeg: fix use-after-free in release path due to uncancelled work X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=34c519feef3e4fcff1078dc8bdb25fbbbd10303f;p=thirdparty%2Fkernel%2Fstable.git media: mtk-jpeg: fix use-after-free in release path due to uncancelled work The mtk_jpeg_release() function frees the context structure (ctx) without first cancelling any pending or running work in ctx->jpeg_work. This creates a race window where the workqueue callback may still be accessing the context memory after it has been freed. Race condition: CPU 0 (release) CPU 1 (workqueue) ---------------- ------------------ close() mtk_jpeg_release() mtk_jpegenc_worker() ctx = work->data // accessing ctx kfree(ctx) // freed! access ctx // UAF! The work is queued via queue_work() during JPEG encode/decode operations (via mtk_jpeg_device_run). If the device is closed while work is pending or running, the work handler will access freed memory. Fix this by calling cancel_work_sync() BEFORE acquiring the mutex. This ordering is critical: if cancel_work_sync() is called after mutex_lock(), and the work handler also tries to acquire the same mutex, it would cause a deadlock. 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 ioctl operations. Fixes: 5fb1c2361e56 ("mtk-jpegenc: add jpeg encode worker interface") Cc: stable@vger.kernel.org Signed-off-by: Fan Wu Reviewed-by: Nicolas Dufresne Signed-off-by: Nicolas Dufresne Signed-off-by: Hans Verkuil --- diff --git a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c index c01124a349f61..8c684756d5fc2 100644 --- a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c +++ b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c @@ -1202,6 +1202,7 @@ static int mtk_jpeg_release(struct file *file) struct mtk_jpeg_dev *jpeg = video_drvdata(file); struct mtk_jpeg_ctx *ctx = mtk_jpeg_file_to_ctx(file); + cancel_work_sync(&ctx->jpeg_work); mutex_lock(&jpeg->lock); v4l2_m2m_ctx_release(ctx->fh.m2m_ctx); v4l2_ctrl_handler_free(&ctx->ctrl_hdl);