From: Guido Vranken <guidovranken@gmail.com>
Date: Mon, 22 Apr 2019 12:11:12 +0000 (+0200)
Subject: Enforce a strict output length check in CRYPTO_ccm128_tag
X-Git-Tag: openssl-3.0.0-alpha1~2131
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=514c9da48b860153079748b0d588cd42191f0b6a;p=oweals%2Fopenssl.git

Enforce a strict output length check in CRYPTO_ccm128_tag

Return error if the output tag buffer size doesn't match
the tag size exactly. This prevents the caller from
using that portion of the tag buffer that remains
uninitialized after an otherwise succesfull call to
CRYPTO_ccm128_tag.

Bug found by OSS-Fuzz.

Fix suggested by Kurt Roeckx.

Signed-off-by: Guido Vranken <guidovranken@gmail.com>

Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8810)
---

diff --git a/crypto/modes/ccm128.c b/crypto/modes/ccm128.c
index 9edf0270e2..bfa2d4604c 100644
--- a/crypto/modes/ccm128.c
+++ b/crypto/modes/ccm128.c
@@ -425,7 +425,7 @@ size_t CRYPTO_ccm128_tag(CCM128_CONTEXT *ctx, unsigned char *tag, size_t len)
 
     M *= 2;
     M += 2;
-    if (len < M)
+    if (len != M)
         return 0;
     memcpy(tag, ctx->cmac.c, M);
     return M;