[PATCH] crypto: arm64/sm4 - Fix possible crash in GCM cryption

[Tianjia Zhang]

When the cryption total length is zero, GCM cryption call
skcipher_walk_done() will cause an unexpected crash, so skip calling
this function to avoid possible crash when the GCM cryption length
is equal to zero.

Fixes: ae1b83c7d572 ("crypto: arm64/sm4 - add CE implementation for GCM mode")
Signed-off-by: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
---
 arch/arm64/crypto/sm4-ce-gcm-glue.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/crypto/sm4-ce-gcm-glue.c b/arch/arm64/crypto/sm4-ce-gcm-glue.c
index c450a2025ca9..9b63bcf9aa85 100644
--- a/arch/arm64/crypto/sm4-ce-gcm-glue.c
+++ b/arch/arm64/crypto/sm4-ce-gcm-glue.c
@@ -178,11 +178,13 @@ static int gcm_crypt(struct aead_request *req, struct skcipher_walk *walk,
 
 		kernel_neon_end();
 
-		err = skcipher_walk_done(walk, tail);
-		if (err)
-			return err;
-		if (walk->nbytes)
-			kernel_neon_begin();
+		if (walk->nbytes) {
+			err = skcipher_walk_done(walk, tail);
+			if (err)
+				return err;
+			if (walk->nbytes)
+				kernel_neon_begin();
+		}
 	} while (walk->nbytes > 0);
 
 	return 0;
-- 
2.24.3 (Apple Git-128)