package/cups: add upstream security fix for CVE-2023-4504

Fixes CVE-2023-4504: Postscript Parsing Heap Overflow

https://github.com/OpenPrinting/cups/security/advisories/GHSA-pf5r-86w9-678h
https://takeonme.org/cves/CVE-2023-4504.html

There is a 2.4.7 release with this fix, but upstream unfortunately broke
!gnutls builds, so backport the security fix instead:

https://github.com/OpenPrinting/cups/issues/762

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/cups/0005-raster-interpret.c-Fix-CVE-2023-4504.patch

@@ -0,0 +1,45 @@
+From 2431caddb7e6a87f04ac90b5c6366ad268b6ff31 Mon Sep 17 00:00:00 2001
+From: Zdenek Dohnal <zdohnal@redhat.com>
+Date: Wed, 20 Sep 2023 14:45:17 +0200
+Subject: [PATCH] raster-interpret.c: Fix CVE-2023-4504
+
+We didn't check for end of buffer if it looks there is an escaped
+character - check for NULL terminator there and if found, return NULL
+as return value and in `ptr`, because a lone backslash is not
+a valid PostScript character.
+
+Upstream: https://github.com/OpenPrinting/cups/commit/2431caddb7e6a87f04ac90b5c6366ad268b6ff31
+[Peter: drop CHANGES hunk]
+Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
+---
+ cups/raster-interpret.c | 14 +++++++++++++-
+ 1 file changed, 14 insertions(+), 1 deletion(-)
+
+diff --git a/cups/raster-interpret.c b/cups/raster-interpret.c
+index 6fcf731b5..b8655c8c6 100644
+--- a/cups/raster-interpret.c
++++ b/cups/raster-interpret.c
+@@ -1116,7 +1116,19 @@ scan_ps(_cups_ps_stack_t *st,		/* I  - Stack */
+ 
+ 	    cur ++;
+ 
+-            if (*cur == 'b')
++	   /*
++	    * Return NULL if we reached NULL terminator, a lone backslash
++	    * is not a valid character in PostScript.
++	    */
++
++	    if (!*cur)
++	    {
++	      *ptr = NULL;
++
++	      return (NULL);
++	    }
++
++	    if (*cur == 'b')
+ 	      *valptr++ = '\b';
+ 	    else if (*cur == 'f')
+ 	      *valptr++ = '\f';
+-- 
+2.30.2
+

package/cups/cups.mk

@@ -13,6 +13,9 @@ CUPS_CPE_ID_VENDOR = openprinting
 CUPS_SELINUX_MODULES = cups
 CUPS_INSTALL_STAGING = YES
 
+# 0005-raster-interpret.c-Fix-CVE-2023-4504.patch
+CUPS_IGNORE_CVES += CVE-2023-4504
+
 # Using autoconf, not autoheader, so we cannot use AUTORECONF = YES.
 define CUPS_RUN_AUTOCONF
 	cd $(@D); $(AUTOCONF) -f