[PATCH 3.12 105/111] crypto: rng - RNGs must return 0 in success case

[Jiri Slaby]

From: Stephan Mueller <smueller@xxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit cde001e4c3c3625c60b68a83eb1f1c2572dee07a upstream.

Change the RNGs to always return 0 in success case.

This patch ensures that seqiv.c works with RNGs other than krng. seqiv
expects that any return code other than 0 is an error. Without the
patch, rfc4106(gcm(aes)) will not work when using a DRBG or an ANSI
X9.31 RNG.

Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 crypto/ansi_cprng.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index 6f5bebc9bf01..765fe7609348 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -210,7 +210,11 @@ static int get_prng_bytes(char *buf, size_t nbytes, struct prng_context *ctx,
 		byte_count = DEFAULT_BLK_SZ;
 	}
 
-	err = byte_count;
+	/*
+	 * Return 0 in case of success as mandated by the kernel
+	 * crypto API interface definition.
+	 */
+	err = 0;
 
 	dbgprint(KERN_CRIT "getting %d random bytes for context %p\n",
 		byte_count, ctx);
-- 
2.4.2

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