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From 2bdc26af43cdd4376bf8e0fdf532bb12dd35d3dd Mon Sep 17 00:00:00 2001
From: "Christoph M. Becker" <cmbecker69@gmx.de>
Date: Mon, 25 Jul 2022 15:58:59 +0200
Subject: [PATCH 2/2] Fix #81726: phar wrapper: DOS when using quine gzip file
The phar wrapper needs to uncompress the file; the uncompressed file
might be compressed, so the wrapper implementation loops. This raises
potential DOS issues regarding too deep or even infinite recursion (the
latter are called compressed file quines[1]). We avoid that by
introducing a recursion limit; we choose the somewhat arbitrary limit
`3`.
This issue has been reported by real_as3617 and gPayl0ad.
[1] <https://honno.dev/gzip-quine/>
(cherry picked from commit 404e8bdb68350931176a5bdc86fc417b34fb583d)
(cherry picked from commit 96fda78bcddd1d793cf2d0ee463dbb49621b577f)
---
NEWS | 2 ++
ext/phar/phar.c | 16 +++++++++++-----
ext/phar/tests/bug81726.gz | Bin 0 -> 204 bytes
ext/phar/tests/bug81726.phpt | 14 ++++++++++++++
4 files changed, 27 insertions(+), 5 deletions(-)
create mode 100644 ext/phar/tests/bug81726.gz
create mode 100644 ext/phar/tests/bug81726.phpt
diff --git a/NEWS b/NEWS
index 90ac6b751b..be8bfd2f98 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,8 @@ PHP NEWS
Backported from 7.4.31
- Core:
+ . Fixed bug #81726: phar wrapper: DOS when using quine gzip file.
+ (CVE-2022-31628). (cmb)
. Fixed bug #81727: Don't mangle HTTP variable names that clash with ones
that have a specific semantic meaning. (CVE-2022-31629). (Derick)
diff --git a/ext/phar/phar.c b/ext/phar/phar.c
index ba76a9b0e0..52c973d7c4 100644
--- a/ext/phar/phar.c
+++ b/ext/phar/phar.c
@@ -1575,7 +1575,8 @@ static int phar_open_from_fp(php_stream* fp, char *fname, int fname_len, char *a
const char zip_magic[] = "PK\x03\x04";
const char gz_magic[] = "\x1f\x8b\x08";
const char bz_magic[] = "BZh";
- char *pos, test = '\0';
+ char *pos;
+ int recursion_count = 3; // arbitrary limit to avoid too deep or even infinite recursion
const int window_size = 1024;
char buffer[1024 + sizeof(token)]; /* a 1024 byte window + the size of the halt_compiler token (moving window) */
const zend_long readsize = sizeof(buffer) - sizeof(token);
@@ -1603,8 +1604,7 @@ static int phar_open_from_fp(php_stream* fp, char *fname, int fname_len, char *a
MAPPHAR_ALLOC_FAIL("internal corruption of phar \"%s\" (truncated entry)")
}
- if (!test) {
- test = '\1';
+ if (recursion_count) {
pos = buffer+tokenlen;
if (!memcmp(pos, gz_magic, 3)) {
char err = 0;
@@ -1664,7 +1664,10 @@ static int phar_open_from_fp(php_stream* fp, char *fname, int fname_len, char *a
compression = PHAR_FILE_COMPRESSED_GZ;
/* now, start over */
- test = '\0';
+ if (!--recursion_count) {
+ MAPPHAR_ALLOC_FAIL("unable to decompress gzipped phar archive \"%s\"");
+ break;
+ }
continue;
} else if (!memcmp(pos, bz_magic, 3)) {
php_stream_filter *filter;
@@ -1702,7 +1705,10 @@ static int phar_open_from_fp(php_stream* fp, char *fname, int fname_len, char *a
compression = PHAR_FILE_COMPRESSED_BZ2;
/* now, start over */
- test = '\0';
+ if (!--recursion_count) {
+ MAPPHAR_ALLOC_FAIL("unable to decompress bzipped phar archive \"%s\"");
+ break;
+ }
continue;
}
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