On Fri, Sep 07, 2007 at 05:09:17PM -0700, Bob Gilligan wrote: > > Proposed patch is below. We found the problem and tested this fix in > 2.6.20, but it looks like the relevant code in blkcipher.c is the same > in the latest tree.
Good catch! I've fixed this slightly differently. Also, the kmalloc size in the case where it does straddle a page isn't enough either. [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 <[EMAIL PROTECTED]> Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} <[EMAIL PROTECTED]> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c index 7755834..469cb7f 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); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
