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[4.2.y-ckt,08/53] crypto: hash - Fix page length clamping in hash walk

Message ID 1464112523-3701-9-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa May 24, 2016, 5:54 p.m. UTC 
4.2.8-ckt11 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

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

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: Kamal Mostafa <kamal@canonical.com>
---
 crypto/ahash.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
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Patch

diff --git a/crypto/ahash.c b/crypto/ahash.c
index d19b523..dac1c24 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)