crypto: authenc - Fix crash with zero-length assoc data

The authenc code doesn't deal with zero-length associated data correctly and ends up constructing a zero-length sg entry which causes a crash when it's fed into the crypto system. This patch fixes this by avoiding the code-path that triggers the SG construction if we have no associated data. This isn't the most optimal fix as it means that we'll end up using the fallback code-path even when we could still execute the digest function. However, this isn't a big deal as nobody but the test path would supply zero-length associated data. Reported-by: Romain Francoise <[email protected]> Signed-off-by: Herbert Xu <[email protected]> Tested-by: Romain Francoise <[email protected]>
josf · Sep 11, 2012 · 9b2f4cb · 9b2f4cb
1 parent 3b75a2c
commit 9b2f4cb
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/crypto/authenc.c b/crypto/authenc.c
@@ -336,7 +336,7 @@ static int crypto_authenc_genicv(struct aead_request *req, u8 *iv,
 		cryptlen += ivsize;
 	}
 
-	if (sg_is_last(assoc)) {
+	if (req->assoclen && sg_is_last(assoc)) {
 		authenc_ahash_fn = crypto_authenc_ahash;
 		sg_init_table(asg, 2);
 		sg_set_page(asg, sg_page(assoc), assoc->length, assoc->offset);
@@ -490,7 +490,7 @@ static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
 		cryptlen += ivsize;
 	}
 
-	if (sg_is_last(assoc)) {
+	if (req->assoclen && sg_is_last(assoc)) {
 		authenc_ahash_fn = crypto_authenc_ahash;
 		sg_init_table(asg, 2);
 		sg_set_page(asg, sg_page(assoc), assoc->length, assoc->offset);