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| author | Herbert Xu <herbert@gondor.apana.org.au> | 2007-09-09 08:45:21 +0100 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2007-09-09 08:45:21 +0100 |
| commit | e4630f9fd8cdc14eb1caa08dafe649eb5ae09985 (patch) | |
| tree | 301b4b69b5780ecfa39c9c1f508d57e47da8af29 | |
| parent | b21010ed6498391c0f359f2a89c907533fe07fec (diff) | |
| download | linux-e4630f9fd8cdc14eb1caa08dafe649eb5ae09985.tar.bz2 | |
[CRYPTO] blkcipher: Fix handling of kmalloc page straddling
The function blkcipher_get_spot tries to return a buffer of
the specified length that does not straddle a page. It has
an off-by-one bug so it may advance a page unnecessarily.
What's worse, one of its callers doesn't provide a buffer
that's sufficiently long for this operation.
This patch fixes both problems. Thanks to Bob Gilligan for
diagnosing this problem and providing a fix.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
| -rw-r--r-- | crypto/blkcipher.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c index 7755834b8846..97586afbe63b 100644 --- a/crypto/blkcipher.c +++ b/crypto/blkcipher.c @@ -59,11 +59,13 @@ static inline void blkcipher_unmap_dst(struct blkcipher_walk *walk) scatterwalk_unmap(walk->dst.virt.addr, 1); } +/* Get a spot of the specified length that does not straddle a page. + * The caller needs to ensure that there is enough space for this operation. + */ static inline u8 *blkcipher_get_spot(u8 *start, unsigned int len) { - if (offset_in_page(start + len) < len) - return (u8 *)((unsigned long)(start + len) & PAGE_MASK); - return start; + u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK); + return start < end_page ? start : end_page; } static inline unsigned int blkcipher_done_slow(struct crypto_blkcipher *tfm, @@ -155,7 +157,8 @@ static inline int blkcipher_next_slow(struct blkcipher_desc *desc, if (walk->buffer) goto ok; - n = bsize * 2 + (alignmask & ~(crypto_tfm_ctx_alignment() - 1)); + n = bsize * 3 - (alignmask + 1) + + (alignmask & ~(crypto_tfm_ctx_alignment() - 1)); walk->buffer = kmalloc(n, GFP_ATOMIC); if (!walk->buffer) return blkcipher_walk_done(desc, walk, -ENOMEM); |