cups: fix CVE-2022-26691

In scheduler/cert.c the previous algorithm didn't expect the strings can
have a different length, so one string can be a substring of the other
and such substring was reported as equal to the longer string.

Backport patch from upstream to fix:
https://github.com/OpenPrinting/cups/commit/de4f8c196106033e4c372dce3e91b9d42b0b9444

CVE: CVE-2022-26691

(From OE-Core rev: cc657868d31cc8b4218a07aa10fa098c379e473c)

Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 35 insertions, 1 deletions

diff --git a/meta/recipes-extended/cups/cups.inc b/meta/recipes-extended/cups/cups.inc
index 15f46937e1..21c56e1430 100644
--- a/meta/recipes-extended/cups/cups.inc
+++ b/meta/recipes-extended/cups/cups.inc
@@ -13,6 +13,7 @@ SRC_URI = "https://github.com/apple/cups/releases/download/v${PV}/${BP}-source.t
            file://0002-don-t-try-to-run-generated-binaries.patch \
            file://0003-cups_1.4.6.bb-Fix-build-on-ppc64.patch \
            file://0004-cups-fix-multilib-install-file-conflicts.patch\
+           file://CVE-2022-26691.patch \
            "
 
 UPSTREAM_CHECK_URI = "https://github.com/apple/cups/releases"
@@ -119,4 +120,4 @@ cups_sysroot_preprocess () {
 
 # -25317 concerns /var/log/cups having lp ownership.  Our /var/log/cups is
 # root:root, so this doesn't apply.
-CVE_CHECK_WHITELIST += "CVE-2021-25317"
\ No newline at end of file
+CVE_CHECK_WHITELIST += "CVE-2021-25317"
diff --git a/meta/recipes-extended/cups/cups/CVE-2022-26691.patch b/meta/recipes-extended/cups/cups/CVE-2022-26691.patch
new file mode 100644
index 0000000000..1fa5a54c70
--- /dev/null
+++ b/meta/recipes-extended/cups/cups/CVE-2022-26691.patch
@@ -0,0 +1,33 @@
+From de4f8c196106033e4c372dce3e91b9d42b0b9444 Mon Sep 17 00:00:00 2001
+From: Zdenek Dohnal <zdohnal@redhat.com>
+Date: Thu, 26 May 2022 06:27:04 +0200
+Subject: [PATCH] scheduler/cert.c: Fix string comparison (fixes
+ CVE-2022-26691)
+
+The previous algorithm didn't expect the strings can have a different
+length, so one string can be a substring of the other and such substring
+was reported as equal to the longer string.
+
+CVE: CVE-2022-26691
+Upstream-Status: Backport [https://github.com/OpenPrinting/cups/commit/de4f8c196106033e4c372dce3e91b9d42b0b9444]
+Signed-off-by: Steve Sakoman
+
+---
+diff --git a/scheduler/cert.c b/scheduler/cert.c
+index b268bf1b2..9b65b96c9 100644
+--- a/scheduler/cert.c
++++ b/scheduler/cert.c
+@@ -434,5 +434,12 @@ ctcompare(const char *a,           /* I - First string */
+     b ++;
+   }
+ 
+-  return (result);
++ /*
++  * The while loop finishes when *a == '\0' or *b == '\0'
++  * so after the while loop either both *a and *b == '\0',
++  * or one points inside a string, so when we apply logical OR on *a,
++  * *b and result, we get a non-zero return value if the compared strings don't match.
++  */
++
++  return (result | *a | *b);
+ }