crypto: hash - Fix page length clamping in hash walk

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>

1 files changed, 2 insertions, 1 deletions

diff --git a/crypto/ahash.c b/crypto/ahash.c
index 5fc1f172963d..3887a98abcc3 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -69,8 +69,9 @@ 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)