ALSA: memalloc: Don't exceed over the requested size

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commit dfef01e150 upstream.

snd_dma_alloc_pages_fallback() tries to allocate pages again when the
allocation fails with reduced size.  But the first try actually
*increases* the size to power-of-two, which may give back a larger
chunk than the requested size.  This confuses the callers, e.g. sgbuf
assumes that the size is equal or less, and it may result in a bad
loop due to the underflow and eventually lead to Oops.

The code of this function seems incorrectly assuming the usage of
get_order().  We need to decrease at first, then align to
power-of-two.

Reported-and-tested-by: he, bo <bo.he@intel.com>
Reported-by: zhang jun <jun.zhang@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

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Takashi Iwai 2018-07-19 11:01:04 +02:00 • committed by Ben Hutchings

parent 4baf01b6d3

commit 2b5854033f

1 changed files with 2 additions and 6 deletions

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sound/core/memalloc.c

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