[PATCH 4.19 136/280] crypto: arm64/aes-ccm - fix bugs in non-NEON fallback routine

[Greg Kroah-Hartman]

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

------------------

From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>

commit 969e2f59d589c15f6aaf306e590dde16f12ea4b3 upstream.

Commit 5092fcf34908 ("crypto: arm64/aes-ce-ccm: add non-SIMD generic
fallback") introduced C fallback code to replace the NEON routines
when invoked from a context where the NEON is not available (i.e.,
from the context of a softirq taken while the NEON is already being
used in kernel process context)

Fix two logical flaws in the MAC calculation of the associated data.

Reported-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Fixes: 5092fcf34908 ("crypto: arm64/aes-ce-ccm: add non-SIMD generic fallback")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/arm64/crypto/aes-ce-ccm-glue.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/arch/arm64/crypto/aes-ce-ccm-glue.c
+++ b/arch/arm64/crypto/aes-ce-ccm-glue.c
@@ -125,7 +125,7 @@ static void ccm_update_mac(struct crypto
 			abytes -= added;
 		}
 
-		while (abytes > AES_BLOCK_SIZE) {
+		while (abytes >= AES_BLOCK_SIZE) {
 			__aes_arm64_encrypt(key->key_enc, mac, mac,
 					    num_rounds(key));
 			crypto_xor(mac, in, AES_BLOCK_SIZE);
@@ -139,8 +139,6 @@ static void ccm_update_mac(struct crypto
 					    num_rounds(key));
 			crypto_xor(mac, in, abytes);
 			*macp = abytes;
-		} else {
-			*macp = 0;
 		}
 	}
 }