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From 6427f1accc54b515bb899370f1a662bfcb1caa52 Mon Sep 17 00:00:00 2001
From: Alexandru Moise <alexandru.moise@windriver.com>
Date: Tue, 7 Feb 2017 11:16:13 +0200
Subject: [PATCH 2/2] crypto/evp: harden AEAD ciphers.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Originally a crash in 32-bit build was reported CHACHA20-POLY1305
cipher. The crash is triggered by truncated packet and is result
of excessive hashing to the edge of accessible memory. Since hash
operation is read-only it is not considered to be exploitable
beyond a DoS condition. Other ciphers were hardened.
Thanks to Robert Święcki for report.
CVE-2017-3731
Backported from upstream commit:
2198b3a55de681e1f3c23edb0586afe13f438051
Upstream-Status: Backport
Reviewed-by: Rich Salz <rsalz@openssl.org>
Signed-off-by: Alexandru Moise <alexandru.moise@windriver.com>
---
crypto/evp/e_aes.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/crypto/evp/e_aes.c b/crypto/evp/e_aes.c
index 1734a82..16dcd10 100644
--- a/crypto/evp/e_aes.c
+++ b/crypto/evp/e_aes.c
@@ -1235,10 +1235,15 @@ static int aes_gcm_ctrl(EVP_CIPHER_CTX *c, int type, int arg, void *ptr)
{
unsigned int len = c->buf[arg - 2] << 8 | c->buf[arg - 1];
/* Correct length for explicit IV */
+ if (len < EVP_GCM_TLS_EXPLICIT_IV_LEN)
+ return 0;
len -= EVP_GCM_TLS_EXPLICIT_IV_LEN;
/* If decrypting correct for tag too */
- if (!c->encrypt)
+ if (!c->encrypt) {
+ if (len < EVP_GCM_TLS_TAG_LEN)
+ return 0;
len -= EVP_GCM_TLS_TAG_LEN;
+ }
c->buf[arg - 2] = len >> 8;
c->buf[arg - 1] = len & 0xff;
}
--
2.10.2
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