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author | Clemens Ladisch <clemens@ladisch.de> | 2010-05-25 09:01:46 +0200 |
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committer | Takashi Iwai <tiwai@suse.de> | 2010-05-25 20:23:48 +0200 |
commit | b406e6103baa3da85950f22d3d46d21a8da654c5 (patch) | |
tree | 3b989503e6d5c75795980a0387c35fcd82c13ee0 /sound/pci | |
parent | 57c7ffc9414d79c8ec25800bbdbf8f801b2f148a (diff) | |
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ALSA: pcm: fix delta calculation at boundary wraparound
In the cleanup of the hw_ptr update functions in 2.6.33, the calculation
of the delta value was changed to use the modulo operator to protect
against a negative difference due to the pointer wrapping around at the
boundary.
However, the ptr variables are unsigned, so a negative difference would
result in the two complement's value which has no relation to the actual
difference relative to the boundary; the result is typically some value
near LONG_MAX-boundary. Furthermore, even if the modulo operation would
be done with signed types, the result of a negative dividend could be
negative.
The invalid delta value is then caught by the following checks, but this
means that the pointer update is ignored.
To fix this, use a range check as in the other pointer calculations.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/pci')
0 files changed, 0 insertions, 0 deletions