[PATCH] crypto: Fix byte counter overflow in SHA-512

[PATCH] crypto: Fix byte counter overflow in SHA-512

[Kent Yoder]

The current code only increments the upper 64 bits of the SHA-512 byte
counter when the number of bytes hashed happens to hit 2^64 exactly.

This patch increments the upper 64 bits whenever the lower 64 bits
overflows.

Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>
---
 crypto/sha512_generic.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/crypto/sha512_generic.c b/crypto/sha512_generic.c
index 107f6f7..dd30f40 100644
--- a/crypto/sha512_generic.c
+++ b/crypto/sha512_generic.c
@@ -174,7 +174,7 @@ sha512_update(struct shash_desc *desc, const u8 *data, unsigned int len)
 	index = sctx->count[0] & 0x7f;
 
 	/* Update number of bytes */
-	if (!(sctx->count[0] += len))
+	if ((sctx->count[0] += len) < len)
 		sctx->count[1]++;
 
         part_len = 128 - index;
-- 
1.7.5.4

Re: [PATCH] crypto: Fix byte counter overflow in SHA-512

[Herbert Xu]

On Fri, Mar 16, 2012 at 08:26:28PM +0000, Kent Yoder wrote:
> The current code only increments the upper 64 bits of the SHA-512 byte
> counter when the number of bytes hashed happens to hit 2^64 exactly.
> 
> This patch increments the upper 64 bits whenever the lower 64 bits
> overflows.
> 
> Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>

Good catch.  Patch applied to crypto and stable.  Thanks a lot!
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt