Validate the return status of kthread_run() during decoder recycling thread initialization to prevent memory leaks, and enforce robust state checking before invoking kthread_stop() to prevent kernel panics.
If the system operates under severe memory constraints, the previous implementation silently accepted error pointers returned by a failed kthread_run() operation. Attempting to pass these invalid error pointers downstream to kthread_stop() during streaming stop or application teardown routines triggered instant kernel panics. Furthermore, when thread initialization failed, the lack of an explicit unwinding path leaked the session's private context (sess->priv) and its associated firmware memory block allocations. Because sess->status was never transitioned to STATUS_INIT, any subsequent call to stop streaming or close the driver file node failed its state validation checks, permanently orphaning active platform DMA assets and codec parameters. Fix these thread lifetime and memory leak bugs via the following: 1. In vdec_start_streaming(), add an explicit IS_ERR() verification barrier immediately following the recycling kthread launch. If thread creation fails, capture the error code via PTR_ERR(), clear the dangling pointer tracking entry to NULL, and jump to a newly added 'err_poweroff' label to unwind hardware settings and clear out allocated structural components cleanly. 2. In vdec_stop_streaming(), protect the teardown execution track by wrapping the kthread_stop() invocation inside a safe !IS_ERR_OR_NULL() conditional block to ensure the target thread structure actually exists in system memory before stopping it. 3. In vdec_close(), cleanly wind down and terminate any lingering recycling threads at the absolute entry boundary of the routine before flushing data framework contexts and releasing the file descriptor matrices to user space. Together, these changes ensure predictable driver behavior, prevent kernel panics during low-memory conditions, and guarantee that memory and DMA assets are fully reclaimed during teardown. Cc: Nicolas Dufresne <[email protected]> Reported-by: Sashiko <[email protected]> Closes: https://lore.kernel.org/all/[email protected]/ Signed-off-by: Anand Moon <[email protected]> --- drivers/staging/media/meson/vdec/vdec.c | 48 +++++++++++++++++++++++-- 1 file changed, 45 insertions(+), 3 deletions(-) diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c index d1f35fc893de1..7fc73d5cdebbf 100644 --- a/drivers/staging/media/meson/vdec/vdec.c +++ b/drivers/staging/media/meson/vdec/vdec.c @@ -32,6 +32,10 @@ struct dummy_buf { /* 16 MiB for parsed bitstream swap exchange */ #define SIZE_VIFIFO SZ_16M +static void vdec_free_canvas(struct amvdec_session *sess); +static void vdec_reset_timestamps(struct amvdec_session *sess); +static void vdec_reset_bufs_recycle(struct amvdec_session *sess); + static u32 get_output_size(u32 width, u32 height) { return ALIGN(width * height, SZ_64K); @@ -353,13 +357,23 @@ static int vdec_start_streaming(struct vb2_queue *q, unsigned int count) sess->sequence_cap = 0; sess->sequence_out = 0; - if (vdec_codec_needs_recycle(sess)) + if (vdec_codec_needs_recycle(sess) && !sess->recycle_thread) { sess->recycle_thread = kthread_run(vdec_recycle_thread, sess, "vdec_recycle"); - + if (IS_ERR(sess->recycle_thread)) { + ret = PTR_ERR(sess->recycle_thread); + sess->recycle_thread = NULL; + goto err_poweroff; + } + } schedule_work(&sess->esparser_queue_work); return 0; +err_poweroff: + vdec_poweroff(sess); + vdec_free_canvas(sess); + vdec_reset_timestamps(sess); + vdec_reset_bufs_recycle(sess); err_free_vififo: if (sess->vififo_vaddr) { dma_free_coherent(sess->core->dev, sess->vififo_size, @@ -464,7 +478,10 @@ static void vdec_stop_streaming(struct vb2_queue *q) if (full_cleanup) { if ((q->type != V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE || !sess->streamon_out) && vdec_codec_needs_recycle(sess)) { - kthread_stop(sess->recycle_thread); + if (!IS_ERR_OR_NULL(sess->recycle_thread)) { + kthread_stop(sess->recycle_thread); + sess->recycle_thread = NULL; + } } vdec_poweroff(sess); @@ -970,6 +987,31 @@ static int vdec_open(struct file *file) static int vdec_close(struct file *file) { struct amvdec_session *sess = file_to_amvdec_session(file); + struct amvdec_core *core = sess->core; + + if (!IS_ERR_OR_NULL(sess->recycle_thread)) { + kthread_stop(sess->recycle_thread); + sess->recycle_thread = NULL; + } + + mutex_lock(&core->lock); + + vdec_poweroff(sess); + vdec_free_canvas(sess); + core->cur_sess = NULL; + + if (sess->vififo_vaddr) { + dma_free_coherent(core->dev, sess->vififo_size, + sess->vififo_vaddr, sess->vififo_paddr); + sess->vififo_vaddr = NULL; + sess->vififo_paddr = 0; + } + vdec_reset_timestamps(sess); + vdec_reset_bufs_recycle(sess); + kfree(sess->priv); + sess->priv = NULL; + + mutex_unlock(&core->lock); v4l2_m2m_ctx_release(sess->m2m_ctx); v4l2_fh_del(&sess->fh, file); -- 2.50.1
