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authorTakashi Iwai <tiwai@suse.de>2018-07-19 11:01:04 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-08-22 07:48:36 +0200
commitdd65a18b208fb2e03824ecf044e41c74b74423c1 (patch)
treea179c3f3787346881f165508a8ecac71f305fc6b /sound
parentad76ea373eb5f1232767242076ffef8b23518602 (diff)
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>
Diffstat (limited to 'sound')
-rw-r--r--sound/core/memalloc.c8
1 files changed, 2 insertions, 6 deletions
diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c
index f05cb6a8cbe0..78ffe445d775 100644
--- a/sound/core/memalloc.c
+++ b/sound/core/memalloc.c
@@ -239,16 +239,12 @@ 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;