From: Helmut Grohne <helmut@...divi.de>
Subject: [PATCH v3] CVE-2022-45142: gsskrb5: fix accidental logic inversions

The referenced commit attempted to fix miscompilations with gcc-9 and
gcc-10 by changing `memcmp(...)` to `memcmp(...) != 0`. Unfortunately,
it also inverted the result of the comparison in two occasions. This
inversion happened during backporting the patch to 7.7.1 and 7.8.0.

Fixes: f6edaafcfefd ("gsskrb5: CVE-2022-3437 Use constant-time memcmp()
 for arcfour unwrap")
Signed-off-by: Helmut Grohne <helmut@...divi.de>
---
 lib/gssapi/krb5/arcfour.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Changes since v1:
 * Fix typo in commit message.
 * Mention 7.8.0 in commit message. Thanks to Jeffrey Altman.

Changes since v2:
 * Add CVE identifier.

NB (Felix Lechner): The message above and the patch below were taken from the
disclosure here: https://www.openwall.com/lists/oss-security/2023/02/08/1

diff --git a/lib/gssapi/krb5/arcfour.c b/lib/gssapi/krb5/arcfour.c
index e838d007a..eee6ad72f 100644
--- a/lib/gssapi/krb5/arcfour.c
+++ b/lib/gssapi/krb5/arcfour.c
@@ -365,7 +365,7 @@ _gssapi_verify_mic_arcfour(OM_uint32 * minor_status,
 	return GSS_S_FAILURE;
     }

-    cmp = (ct_memcmp(cksum_data, p + 8, 8) == 0);
+    cmp = (ct_memcmp(cksum_data, p + 8, 8) != 0);
     if (cmp) {
 	*minor_status = 0;
 	return GSS_S_BAD_MIC;
@@ -730,7 +730,7 @@ OM_uint32 _gssapi_unwrap_arcfour(OM_uint32 *minor_status,
 	return GSS_S_FAILURE;
     }

-    cmp = (ct_memcmp(cksum_data, p0 + 16, 8) == 0); /* SGN_CKSUM */
+    cmp = (ct_memcmp(cksum_data, p0 + 16, 8) != 0); /* SGN_CKSUM */
     if (cmp) {
 	_gsskrb5_release_buffer(minor_status, output_message_buffer);
 	*minor_status = 0;
--
2.38.1
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<div class='path'>path: <a href='/guix/log/?id=457938bbb092e5df375f934076762cb7301298fc'>root</a>/<a href='/guix/log/gnu?id=457938bbb092e5df375f934076762cb7301298fc'>gnu</a>/<a href='/guix/log/gnu/home?id=457938bbb092e5df375f934076762cb7301298fc'>home</a>/<a href='/guix/log/gnu/home/services?id=457938bbb092e5df375f934076762cb7301298fc'>services</a>/<a href='/guix/log/gnu/home/services/messaging.scm?id=457938bbb092e5df375f934076762cb7301298fc'>messaging.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/home/services/messaging.scm?id=457938bbb092e5df375f934076762cb7301298fc&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-03-16 23:03:17 +0100'>2023-03-16</span></td><td><a href='/guix/commit/gnu/home/services/messaging.scm?id=8f219e658d8d2d89a2d6ec10729099130791a3a2'>home: services: kodi, znc, ssh-agent: Use 'match-record'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/home/services/media.scm (home-kodi-services): Use 'match-record'
instead of 'match'.
* gnu/home/services/messaging.scm (home-znc-services): Likewise.
* gnu/home/services/ssh.scm (home-ssh-agent-services): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-03-16 17:29:03 +0100'>2023-03-16</span></td><td><a href='/guix/commit/gnu/home/services/messaging.scm?id=c68648a8a503c59b17ec38107e7c787f3b7370f3'>home: services: znc: Remove host-side use of (shepherd support).</a><span class='msg-avail'>...<span class='msg-tooltip'>This is a followup to 193f547ca35eb49ef57bd9a25b67cb3965f10b03, which
inadvertently pulled in (shepherd support) on the host side.

* gnu/home/services/messaging.scm (home-znc-services): Change 'command' and
'log-file' to gexps.  Add 'modules' field to 'shepherd-service'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-03-16 14:32:50 +0100'>2023-03-16</span></td><td><a href='/guix/commit/gnu/home/services/messaging.scm?id=193f547ca35eb49ef57bd9a25b67cb3965f10b03'>gnu: home: services: Add home-znc-service-type.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/home/services/messaging.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* po/guix/POTFILES.in: Likewise.
* doc/guix.texi (Messaging Home Services): Document it in new subsection.
</span></span></td><td>Jan (janneke) Nieuwenhuizen</td></tr>