crypto: hash - Fix page length clamping in hash walk

commit 13f4bb78cf6a312bbdec367ba3da044b09bf0e29 upstream.

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.

Reported-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/crypto/ahash.c b/crypto/ahash.c
index 7fd8ecf..8271185 100644 (file)
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -64,8 +64,9 @@ 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)