diff options
author | Andrew Morton <akpm@linux-foundation.org> | 2009-01-06 14:43:08 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-06 15:59:30 -0800 |
commit | 0bef3c2dc7d0c8238330785c8f4504761b0e370b (patch) | |
tree | f43e7c7e49f5e67823e7e077c821e8f8d2571e48 /kernel | |
parent | 8375d4909aee4c18798f373ecf24a79f040f75fc (diff) |
dma_alloc_from_coherent(): fix fallback to generic memory
If bitmap_find_free_region() fails and DMA_MEMORY_EXCLUSIVE is not set,
the function will fail to write anything to *ret and will return 1. This will cause dma_alloc_coherent() to return an uninitialised value,
crashing the kernel, perhaps via DMA to a random address.
Fix that by changing it to return zero in this case, so the caller will
proceed to allocate the memory from the generic memory allocator.
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Dmitry Baryshkov <dbaryshkov@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/dma-coherent.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/kernel/dma-coherent.c b/kernel/dma-coherent.c index f013a0c2e11..4bdcea822b4 100644 --- a/kernel/dma-coherent.c +++ b/kernel/dma-coherent.c @@ -116,11 +116,25 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size, int page = bitmap_find_free_region(mem->bitmap, mem->size, order); if (page >= 0) { + /* + * Memory was found in the per-device arena. + */ *dma_handle = mem->device_base + (page << PAGE_SHIFT); *ret = mem->virt_base + (page << PAGE_SHIFT); memset(*ret, 0, size); - } else if (mem->flags & DMA_MEMORY_EXCLUSIVE) + } else if (mem->flags & DMA_MEMORY_EXCLUSIVE) { + /* + * The per-device arena is exhausted and we are not + * permitted to fall back to generic memory. + */ *ret = NULL; + } else { + /* + * The per-device arena is exhausted and we are + * permitted to fall back to generic memory. + */ + return 0; + } } return (mem != NULL); } |