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fix CVE-2023-24805

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zhouwenpei 2023-05-26 08:34:41 +00:00
parent 495cede25b
commit 315b16a244
2 changed files with 225 additions and 2 deletions
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218
backport-CVE-2023-24805.patch Normal file
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@ -0,0 +1,218 @@
From 8f274035756c04efeb77eb654e9d4c4447287d65 Mon Sep 17 00:00:00 2001
From: Till Kamppeter <till.kamppeter@gmail.com>
Date: Wed, 17 May 2023 11:12:37 +0200
Subject: [PATCH] Merge pull request from GHSA-gpxc-v2m8-fr3x
* beh backend: Use execv() instead of system() - CVE-2023-24805
With execv() command line arguments are passed as separate strings and
not the full command line in a single string. This prevents arbitrary
command execution by escaping the quoting of the arguments in a job
with forged job title.
* beh backend: Extra checks against odd/forged input - CVE-2023-24805
- Do not allow '/' in the scheme of the URI (= backend executable
name), to assure that only backends inside /usr/lib/cups/backend/
are used.
- Pre-define scheme buffer to empty string, to be defined for case of
uri being NULL.
- URI must have ':', to split off scheme, otherwise error.
- Check return value of snprintf() to create call path for backend, to
error out on truncation of a too long scheme or on complete failure
due to a completely odd scheme.
* beh backend: Further improvements - CVE-2023-24805
- Use strncat() instead of strncpy() for getting scheme from URI, the latter
does not require setting terminating zero byte in case of truncation.
- Also exclude "." or ".." as scheme, as directories are not valid CUPS
backends.
- Do not use fprintf() in sigterm_handler(), to not interfere with a
fprintf() which could be running in the main process when
sigterm_handler() is triggered.
- Use "static volatile int" for global variable job_canceled.
Reference:https://github.com/OpenPrinting/cups-filters/commit/8f274035756c04efeb77eb654e9d4c4447287d65
Conflict:Adaptation Context
---
backend/beh.c | 110 ++++++++++++++++++++++++++++++++++++++------------
1 file changed, 85 insertions(+), 25 deletions(-)
diff --git a/backend/beh.c b/backend/beh.c
index 225fd27..0b60518 100644
--- a/backend/beh.c
+++ b/backend/beh.c
@@ -22,12 +22,13 @@
#include "backend-private.h"
#include <cups/array.h>
#include <ctype.h>
+#include <sys/wait.h>
/*
* Local globals...
*/
-static int job_canceled = 0; /* Set to 1 on SIGTERM */
+static volatile int job_canceled = 0; // Set to 1 on SIGTERM
/*
* Local functions...
@@ -213,21 +214,44 @@ call_backend(char *uri, /* I - URI of final destination */
char **argv, /* I - Command-line arguments */
char *filename) { /* I - File name of input data */
const char *cups_serverbin; /* Location of programs */
+ char *backend_argv[8]; // Arguments for called CUPS backend
char scheme[1024], /* Scheme from URI */
*ptr, /* Pointer into scheme */
- cmdline[65536]; /* Backend command line */
- int retval;
+ backend_path[2048]; // Backend path
+ int pid,
+ wait_pid,
+ wait_status,
+ retval = 0;
+ int bytes;
+
/*
* Build the backend command line...
*/
- strncpy(scheme, uri, sizeof(scheme) - 1);
- if (strlen(uri) > 1023)
- scheme[1023] = '\0';
+ scheme[0] = '\0';
+ strncat(scheme, uri, sizeof(scheme) - 1);
if ((ptr = strchr(scheme, ':')) != NULL)
*ptr = '\0';
-
+ else
+ {
+ fprintf(stderr,
+ "ERROR: beh: Invalid URI, no colon (':') to mark end of scheme part.\n");
+ exit (CUPS_BACKEND_FAILED);
+ }
+ if (strchr(scheme, '/'))
+ {
+ fprintf(stderr,
+ "ERROR: beh: Invalid URI, scheme contains a slash ('/').\n");
+ exit (CUPS_BACKEND_FAILED);
+ }
+ if (!strcmp(scheme, ".") || !strcmp(scheme, ".."))
+ {
+ fprintf(stderr,
+ "ERROR: beh: Invalid URI, scheme (\"%s\") is a directory.\n",
+ scheme);
+ exit (CUPS_BACKEND_FAILED);
+ }
if ((cups_serverbin = getenv("CUPS_SERVERBIN")) == NULL)
cups_serverbin = CUPS_SERVERBIN;
@@ -235,16 +259,26 @@ call_backend(char *uri, /* I - URI of final destination */
fprintf(stderr,
"ERROR: beh: Direct output into a file not supported.\n");
exit (CUPS_BACKEND_FAILED);
- } else
- snprintf(cmdline, sizeof(cmdline),
- "%s/backend/%s '%s' '%s' '%s' '%s' '%s' %s",
- cups_serverbin, scheme, argv[1], argv[2], argv[3],
- /* Apply number of copies only if beh was called with a
- file name and not with the print data in stdin, as
- backends should handle copies only if they are called
- with a file name */
- (argc == 6 ? "1" : argv[4]),
- argv[5], filename);
+ }
+
+ backend_argv[0] = uri;
+ backend_argv[1] = argv[1];
+ backend_argv[2] = argv[2];
+ backend_argv[3] = argv[3];
+ backend_argv[4] = (argc == 6 ? "1" : argv[4]);
+ backend_argv[5] = argv[5];
+ backend_argv[6] = filename;
+ backend_argv[7] = NULL;
+
+ bytes = snprintf(backend_path, sizeof(backend_path),
+ "%s/backend/%s", cups_serverbin, scheme);
+ if (bytes < 0 || bytes >= sizeof(backend_path))
+ {
+ fprintf(stderr,
+ "ERROR: beh: Invalid scheme (\"%s\"), could not determing backend path.\n",
+ scheme);
+ exit (CUPS_BACKEND_FAILED);
+ }
/*
* Overwrite the device URI and run the actual backend...
@@ -253,17 +287,41 @@ call_backend(char *uri, /* I - URI of final destination */
setenv("DEVICE_URI", uri, 1);
fprintf(stderr,
- "DEBUG: beh: Executing backend command line \"%s\"...\n",
- cmdline);
+ "DEBUG: beh: Executing backend command line \"%s '%s' '%s' '%s' '%s' '%s'%s%s\"...\n",
+ backend_path, backend_argv[1], backend_argv[2], backend_argv[3],
+ backend_argv[4], backend_argv[5],
+ (backend_argv[6] && backend_argv[6][0] ? " " : ""),
+ (backend_argv[6] && backend_argv[6][0] ? backend_argv[6] : ""));
fprintf(stderr,
"DEBUG: beh: Using device URI: %s\n",
uri);
- retval = system(cmdline) >> 8;
+ if ((pid = fork()) == 0)
+ {
+ retval = execv(backend_path, backend_argv);
- if (retval == -1)
- fprintf(stderr, "ERROR: Unable to execute backend command line: %s\n",
- strerror(errno));
+ if (retval == -1)
+ fprintf(stderr, "ERROR: Unable to execute backend: %s\n",
+ strerror(errno));
+ exit (CUPS_BACKEND_FAILED);
+ }
+ else if (pid < 0)
+ {
+ fprintf(stderr, "ERROR: Unable to fork for backend\n");
+ return (CUPS_BACKEND_FAILED);
+ }
+
+ while ((wait_pid = wait(&wait_status)) < 0 && errno == EINTR);
+
+ if (wait_pid >= 0 && wait_status)
+ {
+ if (WIFEXITED(wait_status))
+ retval = WEXITSTATUS(wait_status);
+ else if (WTERMSIG(wait_status) != SIGTERM)
+ retval = WTERMSIG(wait_status);
+ else
+ retval = 0;
+ }
return (retval);
}
@@ -277,8 +335,10 @@ static void
sigterm_handler(int sig) { /* I - Signal number (unused) */
(void)sig;
- fprintf(stderr,
- "DEBUG: beh: Job canceled.\n");
+ const char * const msg = "DEBUG: beh: Job canceled.\n";
+ // The if() is to eliminate the return value and silence the warning
+ // about an unused return value.
+ if (write(2, msg, strlen(msg)));
if (job_canceled)
_exit(CUPS_BACKEND_OK);
--
2.33.0

9
cups-filters.spec
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@ -2,11 +2,13 @@
Summary: OpenPrinting CUPS filters, backends, and cups-browsed
Name: cups-filters
Version: 1.28.15
Release: 1
Release: 2
License: GPLv2 and GPLv2+ and GPLv3 and GPLv3+ and LGPLv2+ and MIT and BSD with advertising
Url: http://www.linuxfoundation.org/collaborate/workgroups/openprinting/cups-filters
Source0: http://www.openprinting.org/download/cups-filters/cups-filters-%{version}.tar.xz
Patch6000: backport-CVE-2023-24805.patch
BuildRequires: pkgconf-pkg-config pkgconfig(libqpdf) pkgconfig(libpng) pkgconfig(dbus-1)
BuildRequires: poppler-cpp-devel libtiff-devel avahi-devel libjpeg-turbo-devel pkgconfig(zlib)
BuildRequires: pkgconfig(ijs) pkgconfig(freetype2) pkgconfig(lcms2) pkgconfig(poppler)
@ -158,10 +160,13 @@ fi
%{_mandir}/man8/cups-browsed.8.gz
%changelog
* Fri May 26 2023 zhouwenpei <zhouwenpei1@h-partners.com> - 1.28.15-2
- fix CVE-2023-24805
* Wed Aug 31 2022 tianlijing <tianlijing@kylinos.cn> - 1.28.15-1
- update to 1.28.15
* Mon Jan 10 2021 hanhui <hanhui15@huawei.com> - 1.28.9-2
* Sun Jan 10 2021 hanhui <hanhui15@huawei.com> - 1.28.9-2
- fix build err,can not find foomatic-rip
* Fri Jul 30 2021 yushaogui <yusahogui@huawei.com> - 1.28.9-1