[added to the 3.18 stable tree] crypto: hash - Fix page length clamping in hash walk

Sasha Levin
2016-05-19T04:17:57Z

From: Herbert Xu <herbert@gondor.apana.org.au>

This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit 13f4bb78cf6a312bbdec367ba3da044b09bf0e29 ]

The crypto hash walk code is broken when supplied with an offset
greater than or equal to PAGE_SIZE. This patch fixes it by adjusting
walk->pg and walk->offset when this happens.

Cc: <stable@vger.kernel.org>
Reported-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
crypto/ahash.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/crypto/ahash.c b/crypto/ahash.c
index 51d48cd..46ab909 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -68,8 +68,9 @@ static int hash_walk_new_entry(struct crypto_hash_walk *walk)
struct scatterlist *sg;

sg = walk->sg;
- walk->pg = sg_page(sg);
walk->offset = sg->offset;
+ walk->pg = sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
+ walk->offset = offset_in_page(walk->offset);
walk->entrylen = sg->length;

if (walk->entrylen > walk->total)
--
2.5.0