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crypto: hash - Fix handling of small unaligned buffers 

If a scatterwalk chain contains an entry with an unaligned offset then
hash_walk_next() will cut off the next step at the next alignment point.

However, if the entry ends before the next alignment point then we a loop,
which leads to a kernel oops.

Fix this by checking whether the next aligment point is before the end of the
current entry.

Signed-off-by: Szilveszter Ördög <slipszi@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Szilveszter Ördög 2010-08-06 09:26:38 +08:00 committed by Herbert Xu
parent fc1caf6eaf
commit 23a75eee07
1 changed files with 5 additions and 2 deletions
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7
crypto/ahash.c
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@ -47,8 +47,11 @@ static int hash_walk_next(struct crypto_hash_walk *walk)
walk->data = crypto_kmap(walk->pg, 0);
walk->data += offset;
if (offset & alignmask)
nbytes = alignmask + 1 - (offset & alignmask);
if (offset & alignmask) {
unsigned int unaligned = alignmask + 1 - (offset & alignmask);
if (nbytes > unaligned)
nbytes = unaligned;
}
walk->entrylen -= nbytes;
return nbytes;