[Devel] [PATCH RHEL7 COMMIT] ms/crypto: hash - Fix page length clamping in hash walk

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-327.36.1.vz7.19.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.36.1.vz7.19.3
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commit 2c7d841fc1d4c3a1c3d2afb3f21d63020b6656da
Author: Herbert Xu <herbert at gondor.apana.org.au>
Date:   Mon Oct 24 16:34:08 2016 +0400

    ms/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 at vger.kernel.org>
    Reported-by: Steffen Klassert <steffen.klassert at secunet.com>
    Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
    (cherry picked from commit 13f4bb78cf6a312bbdec367ba3da044b09bf0e29)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 crypto/ahash.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/crypto/ahash.c b/crypto/ahash.c
index 8444019..ad96ce0 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)