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authorLinus Torvalds <torvalds@linux-foundation.org>2009-03-12 19:32:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-03-12 19:32:51 -0700
commitaa8e4fc68d8024cd3132035d13c3cefa7baeac8f (patch)
treeace4457c20730a5a557f91599ba30274a89c46a8
parent9ead64974b05501bbac0d63a47c99fa786d064ba (diff)
bitmap: fix end condition in bitmap_find_free_region
Guennadi Liakhovetski noticed that the end condition for the loop in bitmap_find_free_region() is wrong, and the "return if error" was also using the wrong conditional that would only trigger if the bitmap was an exact multiple of the allocation size, which is not necessarily the case with dma_alloc_from_coherent(). Such a failure would end up in bitmap_find_free_region() accessing beyond the end of the bitmap. Reported-by: Guennadi Liakhovetski <lg@denx.de> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--lib/bitmap.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 1338469ac849..35a1f7ff4149 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -948,15 +948,15 @@ done:
*/
int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
{
- int pos; /* scans bitmap by regions of size order */
+ int pos, end; /* scans bitmap by regions of size order */
- for (pos = 0; pos < bits; pos += (1 << order))
- if (__reg_op(bitmap, pos, order, REG_OP_ISFREE))
- break;
- if (pos == bits)
- return -ENOMEM;
- __reg_op(bitmap, pos, order, REG_OP_ALLOC);
- return pos;
+ for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) {
+ if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
+ continue;
+ __reg_op(bitmap, pos, order, REG_OP_ALLOC);
+ return pos;
+ }
+ return -ENOMEM;
}
EXPORT_SYMBOL(bitmap_find_free_region);