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| author | Takashi Iwai <tiwai@suse.de> | 2018-07-19 11:01:04 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-08-22 07:43:41 +0200 |
| commit | efa72756f954a097c094260a275b2ea1c81fcef2 (patch) | |
| tree | 37f316db0c9d9afa1043694e659d4f7b1b8ef76a | |
| parent | 29a1683215174b1e64851c33d90468993560fcf5 (diff) | |
| download | linux-efa72756f954a097c094260a275b2ea1c81fcef2.tar.gz | |
ALSA: memalloc: Don't exceed over the requested size
commit dfef01e150824b0e6da750cacda8958188d29aea 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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | sound/core/memalloc.c | 8 |
1 files changed, 2 insertions, 6 deletions
diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c index 7f89d3c79a4b7..753d5fc4b284f 100644 --- a/sound/core/memalloc.c +++ b/sound/core/memalloc.c @@ -242,16 +242,12 @@ int snd_dma_alloc_pages_fallback(int type, struct device *device, size_t size, int err; while ((err = snd_dma_alloc_pages(type, device, size, dmab)) < 0) { - size_t aligned_size; if (err != -ENOMEM) return err; if (size <= PAGE_SIZE) return -ENOMEM; - aligned_size = PAGE_SIZE << get_order(size); - if (size != aligned_size) - size = aligned_size; - else - size >>= 1; + size >>= 1; + size = PAGE_SIZE << get_order(size); } if (! dmab->area) return -ENOMEM; |