Messages in this thread Patch in this message |  | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 13/22] ALSA: memalloc: Dont exceed over the requested size | Date | Tue, 21 Aug 2018 08:21:39 +0200 |
| |
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Takashi Iwai <tiwai@suse.de>
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>
--- sound/core/memalloc.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)
--- a/sound/core/memalloc.c +++ b/sound/core/memalloc.c @@ -239,16 +239,12 @@ int snd_dma_alloc_pages_fallback(int typ 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;
|  |