From: Qualys Security Advisory <qsa@qualys.com>
Date: Mon, 22 Feb 2021 02:54:16 +0000 (-0800)
Subject: CVE-2020-28025: Heap out-of-bounds read in pdkim_finish_bodyhash()
X-Git-Tag: exim-4.94.1~23
X-Git-Url: https://git.exim.org/exim.git/commitdiff_plain/1c261b90f627f0489f7dfcf1e66b46cce67f477d?ds=inline

CVE-2020-28025: Heap out-of-bounds read in pdkim_finish_bodyhash()

(cherry picked from commit cad30cd3fb96196e908e0d66b1b45fdf377c850c)
---

diff --git a/src/src/pdkim/pdkim.c b/src/src/pdkim/pdkim.c
index 4c73d4fac..4320ecd49 100644
--- a/src/src/pdkim/pdkim.c
+++ b/src/src/pdkim/pdkim.c
@@ -825,7 +825,7 @@ for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next)
   /* VERIFICATION --------------------------------------------------------- */
   /* Be careful that the header sig included a bodyash */
 
-    if (  sig->bodyhash.data
+    if (sig->bodyhash.data && sig->bodyhash.len == b->bh.len
        && memcmp(b->bh.data, sig->bodyhash.data, b->bh.len) == 0)
       {
       DEBUG(D_acl) debug_printf("DKIM [%s] Body hash compared OK\n", sig->domain);