This corresponds to upstream changesets e4630f9fd8cdc14eb1caa08dafe649eb5ae09985 and 32528d0fbda1093eeeaa7d0a2c498bbb5154099d. [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 Signed-off-by: Greg Kroah-Hartman --- crypto/blkcipher.c | 11 +++++++---- 1 files changed, 7 insertions(+), 4 deletions(-) Index: 2.6/crypto/blkcipher.c =================================================================== --- 2.6.orig/crypto/blkcipher.c +++ 2.6/crypto/blkcipher.c @@ -58,11 +58,13 @@ static inline void blkcipher_unmap_dst(s 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, @@ -154,7 +156,8 @@ static inline int blkcipher_next_slow(st 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); -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/