crypto: authencesn - Fix digest_null crash

When authencesn is used together with digest_null a crash will occur on the decrypt path. This is because normally we perform a special setup to preserve the ESN, but this is skipped if there is no authentication. However, on the post-authentication path it always expects the preservation to be in place, thus causing a crash when digest_null is used. This patch fixes this by also skipping the post-processing when there is no authentication. Fixes: 104880a ("crypto: authencesn - Convert to new AEAD...") Cc: <[email protected]> Reported-by: Jan Tluka <[email protected]> Signed-off-by: Herbert Xu <[email protected]>
chewitt · Jul 18, 2017 · 41cdf7a · 41cdf7a
1 parent efc856e
commit 41cdf7a
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/crypto/authencesn.c b/crypto/authencesn.c
@@ -248,6 +248,9 @@ static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 	u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 	u32 tmp[2];
 
+	if (!authsize)
+		goto decrypt;
+
 	/* Move high-order bits of sequence number back. */
 	scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 	scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
@@ -256,6 +259,8 @@ static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 	if (crypto_memneq(ihash, ohash, authsize))
 		return -EBADMSG;
 
+decrypt:
+
 	sg_init_table(areq_ctx->dst, 2);
 	dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);