ALSA: timer: Fix negative queue usage by racy accesses

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commit 3fa6993fef upstream.

The user timer tu->qused counter may go to a negative value when
multiple concurrent reads are performed since both the check and the
decrement of tu->qused are done in two individual locked contexts.
This results in bogus read outs, and the endless loop in the
user-space side.

The fix is to move the decrement of the tu->qused counter into the
same spinlock context as the zero-check of the counter.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Takashi Iwai 2016-07-04 14:02:15 +02:00 • committed by Greg Kroah-Hartman

parent 02a49fd9d0

commit 547d982b7e

1 changed files with 1 additions and 1 deletions

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sound/core/timer.c

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