mirror of https://gitee.com/openkylin/linux.git
ALSA: usb-audio: Fix racy list management in output queue
The linked list entry from FIFO is peeked at
queue_pending_output_urbs() but the actual element pop-out is
performed outside the spinlock, and it's potentially racy.
Do delete the link at the right place inside the spinlock.
Fixes: 8fdff6a319
("ALSA: snd-usb: implement new endpoint streaming model")
Link: https://lore.kernel.org/r/20200424074016.14301-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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@ -346,17 +346,17 @@ static void queue_pending_output_urbs(struct snd_usb_endpoint *ep)
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ep->next_packet_read_pos %= MAX_URBS;
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/* take URB out of FIFO */
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if (!list_empty(&ep->ready_playback_urbs))
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if (!list_empty(&ep->ready_playback_urbs)) {
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ctx = list_first_entry(&ep->ready_playback_urbs,
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struct snd_urb_ctx, ready_list);
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list_del_init(&ctx->ready_list);
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}
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}
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spin_unlock_irqrestore(&ep->lock, flags);
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if (ctx == NULL)
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return;
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list_del_init(&ctx->ready_list);
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/* copy over the length information */
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for (i = 0; i < packet->packets; i++)
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ctx->packet_size[i] = packet->packet_size[i];
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