From: Pascal van Leeuwen <pascalvanl@gmail.com>
Date: Fri, 9 Aug 2019 15:51:07 +0000 (+0200)
Subject: crypto: aead - Do not allow authsize=0 if auth. alg has digestsize>0
X-Git-Tag: v5.4.17~2708^2~153
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=a62084d299d950f2ad0649caf9a9b9a431346996;p=arm%2Flinux.git

crypto: aead - Do not allow authsize=0 if auth. alg has digestsize>0

Return -EINVAL on an attempt to set the authsize to 0 with an auth.
algorithm with a non-zero digestsize (i.e. anything but digest_null)
as authenticating the data and then throwing away the result does not
make any sense at all.

The digestsize zero exception is for use with digest_null for testing
purposes only.

Signed-off-by: Pascal van Leeuwen <pvanleeuwen@verimatrix.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

diff --git a/crypto/aead.c b/crypto/aead.c
index fbf0ec93bc8e..ce035589cf57 100644
--- a/crypto/aead.c
+++ b/crypto/aead.c
@@ -70,7 +70,8 @@ int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
 {
 	int err;
 
-	if (authsize > crypto_aead_maxauthsize(tfm))
+	if ((!authsize && crypto_aead_maxauthsize(tfm)) ||
+	    authsize > crypto_aead_maxauthsize(tfm))
 		return -EINVAL;
 
 	if (crypto_aead_alg(tfm)->setauthsize) {