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From 4b7d9cd4a018898d7714ce06f3faf2626c14582b Mon Sep 17 00:00:00 2001
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From: Werner Koch <wk@gnupg.org>
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Date: Wed, 5 Oct 2022 14:19:06 +0200
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Subject: [PATCH] Detect a possible overflow directly in the TLV parser.
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* src/ber-help.c (_ksba_ber_read_tl): Check for overflow of a commonly
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used sum.
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--
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It is quite common to have checks like
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if (ti.nhdr + ti.length >= DIM(tmpbuf))
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return gpg_error (GPG_ERR_TOO_LARGE);
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This patch detects possible integer overflows immmediately when
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creating the TI object.
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Reported-by: ZDI-CAN-18927, ZDI-CAN-18928, ZDI-CAN-18929
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---
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src/ber-help.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/src/ber-help.c b/src/ber-help.c
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index 81c31ed..56efb6a 100644
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--- a/src/ber-help.c
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+++ b/src/ber-help.c
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@@ -182,6 +182,12 @@ _ksba_ber_read_tl (ksba_reader_t reader, struct tag_info *ti)
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ti->length = len;
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}
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+ if (ti->length > ti->nhdr && (ti->nhdr + ti->length) < ti->length)
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+ {
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+ ti->err_string = "header+length would overflow";
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+ return gpg_error (GPG_ERR_EOVERFLOW);
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+ }
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+
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/* Without this kludge some example certs can't be parsed */
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if (ti->class == CLASS_UNIVERSAL && !ti->tag)
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ti->length = 0;
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--
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2.37.3
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commit f61a5ea4e0f6a80fd4b28ef0174bee77793cf070
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Author: Werner Koch <wk@gnupg.org>
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Date: Tue Nov 22 16:36:46 2022 +0100
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Fix an integer overflow in the CRL signature parser.
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* src/crl.c (parse_signature): N+N2 now checked for overflow.
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* src/ocsp.c (parse_response_extensions): Do not accept too large
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values.
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(parse_single_extensions): Ditto.
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--
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The second patch is an extra safegourd not related to the reported
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bug.
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GnuPG-bug-id: 6284
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Reported-by: Joseph Surin, elttam
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diff --git a/src/crl.c b/src/crl.c
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index 9f71c85..2e6ca29 100644
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--- a/src/crl.c
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+++ b/src/crl.c
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@@ -1349,7 +1349,7 @@ parse_signature (ksba_crl_t crl)
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&& !ti.is_constructed) )
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return gpg_error (GPG_ERR_INV_CRL_OBJ);
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n2 = ti.nhdr + ti.length;
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- if (n + n2 >= DIM(tmpbuf))
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+ if (n + n2 >= DIM(tmpbuf) || (n + n2) < n)
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return gpg_error (GPG_ERR_TOO_LARGE);
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memcpy (tmpbuf+n, ti.buf, ti.nhdr);
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err = read_buffer (crl->reader, tmpbuf+n+ti.nhdr, ti.length);
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diff --git a/src/ocsp.c b/src/ocsp.c
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index d4cba04..657d15f 100644
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--- a/src/ocsp.c
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+++ b/src/ocsp.c
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@@ -721,6 +721,12 @@ parse_response_extensions (ksba_ocsp_t ocsp,
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else
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ocsp->good_nonce = 1;
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}
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+ if (ti.length > (1<<24))
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+ {
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+ /* Bail out on much too large objects. */
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+ err = gpg_error (GPG_ERR_BAD_BER);
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+ goto leave;
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+ }
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ex = xtrymalloc (sizeof *ex + strlen (oid) + ti.length);
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if (!ex)
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{
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@@ -788,6 +794,12 @@ parse_single_extensions (struct ocsp_reqitem_s *ri,
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err = parse_octet_string (&data, &datalen, &ti);
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if (err)
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goto leave;
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+ if (ti.length > (1<<24))
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+ {
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+ /* Bail out on much too large objects. */
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+ err = gpg_error (GPG_ERR_BAD_BER);
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+ goto leave;
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+ }
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ex = xtrymalloc (sizeof *ex + strlen (oid) + ti.length);
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if (!ex)
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{
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