From ed0ee0ce0a3224dab5caa088a5f8b6df25924276 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Tue, 27 Mar 2012 05:51:00 -0300 Subject: [PATCH] [media] uvcvideo: Fix race-related crash in uvc_video_clock_update() The driver frees the clock samples buffer before stopping the video buffers queue. If a DQBUF call arrives in-between, uvc_video_clock_update() will be called with a NULL clock samples buffer, leading to a crash. This occurs very frequently when using the webcam with the flash browser plugin. Move clock initialization/cleanup to uvc_video_enable() in order to free the clock samples buffer after the queue is stopped. Make sure the clock is reset at resume time to avoid miscalculating timestamps. Signed-off-by: Laurent Pinchart Cc: stable@vger.kernel.org Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/uvc/uvc_video.c | 50 ++++++++++++++++++----------- 1 file changed, 32 insertions(+), 18 deletions(-) diff --git a/drivers/media/video/uvc/uvc_video.c b/drivers/media/video/uvc/uvc_video.c index 4a44f9a1bae0..b76b0ac0958f 100644 --- a/drivers/media/video/uvc/uvc_video.c +++ b/drivers/media/video/uvc/uvc_video.c @@ -468,22 +468,30 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf, spin_unlock_irqrestore(&stream->clock.lock, flags); } -static int uvc_video_clock_init(struct uvc_streaming *stream) +static void uvc_video_clock_reset(struct uvc_streaming *stream) { struct uvc_clock *clock = &stream->clock; - spin_lock_init(&clock->lock); clock->head = 0; clock->count = 0; - clock->size = 32; clock->last_sof = -1; clock->sof_offset = -1; +} + +static int uvc_video_clock_init(struct uvc_streaming *stream) +{ + struct uvc_clock *clock = &stream->clock; + + spin_lock_init(&clock->lock); + clock->size = 32; clock->samples = kmalloc(clock->size * sizeof(*clock->samples), GFP_KERNEL); if (clock->samples == NULL) return -ENOMEM; + uvc_video_clock_reset(stream); + return 0; } @@ -1424,8 +1432,6 @@ static void uvc_uninit_video(struct uvc_streaming *stream, int free_buffers) if (free_buffers) uvc_free_urb_buffers(stream); - - uvc_video_clock_cleanup(stream); } /* @@ -1555,10 +1561,6 @@ static int uvc_init_video(struct uvc_streaming *stream, gfp_t gfp_flags) uvc_video_stats_start(stream); - ret = uvc_video_clock_init(stream); - if (ret < 0) - return ret; - if (intf->num_altsetting > 1) { struct usb_host_endpoint *best_ep = NULL; unsigned int best_psize = 3 * 1024; @@ -1683,6 +1685,8 @@ int uvc_video_resume(struct uvc_streaming *stream, int reset) stream->frozen = 0; + uvc_video_clock_reset(stream); + ret = uvc_commit_video(stream, &stream->ctrl); if (ret < 0) { uvc_queue_enable(&stream->queue, 0); @@ -1819,25 +1823,35 @@ int uvc_video_enable(struct uvc_streaming *stream, int enable) uvc_uninit_video(stream, 1); usb_set_interface(stream->dev->udev, stream->intfnum, 0); uvc_queue_enable(&stream->queue, 0); + uvc_video_clock_cleanup(stream); return 0; } - ret = uvc_queue_enable(&stream->queue, 1); + ret = uvc_video_clock_init(stream); if (ret < 0) return ret; + ret = uvc_queue_enable(&stream->queue, 1); + if (ret < 0) + goto error_queue; + /* Commit the streaming parameters. */ ret = uvc_commit_video(stream, &stream->ctrl); - if (ret < 0) { - uvc_queue_enable(&stream->queue, 0); - return ret; - } + if (ret < 0) + goto error_commit; ret = uvc_init_video(stream, GFP_KERNEL); - if (ret < 0) { - usb_set_interface(stream->dev->udev, stream->intfnum, 0); - uvc_queue_enable(&stream->queue, 0); - } + if (ret < 0) + goto error_video; + + return 0; + +error_video: + usb_set_interface(stream->dev->udev, stream->intfnum, 0); +error_commit: + uvc_queue_enable(&stream->queue, 0); +error_queue: + uvc_video_clock_cleanup(stream); return ret; } -- 2.20.1