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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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