Detect a possible overflow directly in the TLV parser.

Resolves: rhbz#2135703

libksba-1.5.1-overflow.patch

@@ -0,0 +1,42 @@
+From 4b7d9cd4a018898d7714ce06f3faf2626c14582b Mon Sep 17 00:00:00 2001
+From: Werner Koch <wk@gnupg.org>
+Date: Wed, 5 Oct 2022 14:19:06 +0200
+Subject: [PATCH] Detect a possible overflow directly in the TLV parser.
+
+* src/ber-help.c (_ksba_ber_read_tl): Check for overflow of a commonly
+used sum.
+--
+
+It is quite common to have checks like
+
+    if (ti.nhdr + ti.length >= DIM(tmpbuf))
+       return gpg_error (GPG_ERR_TOO_LARGE);
+
+This patch detects possible integer overflows immmediately when
+creating the TI object.
+
+Reported-by: ZDI-CAN-18927, ZDI-CAN-18928, ZDI-CAN-18929
+---
+ src/ber-help.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/src/ber-help.c b/src/ber-help.c
+index 81c31ed..56efb6a 100644
+--- a/src/ber-help.c
++++ b/src/ber-help.c
+@@ -182,6 +182,12 @@ _ksba_ber_read_tl (ksba_reader_t reader, struct tag_info *ti)
+       ti->length = len;
+     }
+ 
++  if (ti->length > ti->nhdr && (ti->nhdr + ti->length) < ti->length)
++    {
++      ti->err_string = "header+length would overflow";
++      return gpg_error (GPG_ERR_EOVERFLOW);
++    }
++
+   /* Without this kludge some example certs can't be parsed */
+   if (ti->class == CLASS_UNIVERSAL && !ti->tag)
+     ti->length = 0;
+-- 
+2.37.3
+

libksba.spec

@@ -12,6 +12,8 @@ Source1: https://www.gnupg.org/ftp/gcrypt/libksba/libksba-%{version}.tar.bz2.sig
 
 Patch1: libksba-1.3.0-multilib.patch
 Patch2: libksba-1.5.1-coverity.patch
+# Fix for CVE-2022-3515
+Patch3: libksba-1.5.1-overflow.patch
 
 BuildRequires: gcc
 BuildRequires: gawk
@@ -38,6 +40,7 @@ Requires: pkgconfig
 
 %patch1 -p1 -b .multilib
 %patch2 -p1 -b .coverity
+%patch3 -p1 -b .overflow
 
 # Convert to utf-8
 for file in THANKS; do