From 8b40e8021a98728b5889516af308dd52378c964c Mon Sep 17 00:00:00 2001
From: Lv Ying <lvying6@huawei.com>
Date: Wed, 23 Feb 2022 09:32:21 +0800
Subject: [PATCH 2/2] fix CVE-2022-0529 Heap out-of-bound writes and reads
 during conversion of wide string to local string
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CVE-2022-0529 discussed in https://bugzilla.redhat.com/show_bug.cgi?id=2051402
CVE can be reproduced:
$ unset LANG
$ valgrind ./unzip ./unzip_03/testcase
valgrind will detect Heap out-of-bound writes and reads just as bugzilla discussed

This is because wide_to_escape_string returns a string that represents a wide char
not in local char set, is longer than MAX_ESCAPE_BYTES(8). Actually, MAX_ESCAPE_BYTES
max is 10, for example, 4-byte wide character '#L02020276' is 10 bytes long, not
including the terminating null character. So strcat(buffer, escape_string) will cause
Heap out-of-bound writes.

By default, the OS vendor sets the LANG environment variable. valgrind tests this POC
will get another memory error.
$ export | grep LANG
declare -x LANG="en_US.UTF-8"
$ valgrind ./unzip ./unzip_03/testcase

Archive:  unzip_03/testcase
warning [unzip_03/testcase]:  303 extra bytes at beginning or within zipfile
  (attempting to process anyway)
error [unzip_03/testcase]:  reported length of central directory is
  -303 bytes too long (Atari STZip zipfile?  J.H.Holm ZIPSPLIT 1.1
  zipfile?).  Compensating...
==15725== Conditional jump or move depends on uninitialised value(s)
==15725==    at 0x4903169: __wcsnlen_sse4_1 (strlen.S:186)
==15725==    by 0x48F3D61: wcsrtombs (wcsrtombs.c:104)
==15725==    by 0x488B9A0: wcstombs (wcstombs.c:34)
==15725==    by 0x407279: wcstombs (stdlib.h:154)
==15725==    by 0x407279: fnfilter.constprop.2 (extract.c:2946)
==15725==    by 0x4076A5: store_info (extract.c:1155)
==15725==    by 0x40AFF4: extract_or_test_files (extract.c:782)
==15725==    by 0x41586C: do_seekable (process.c:994)
==15725==    by 0x4167EE: process_zipfiles (process.c:401)
==15725==    by 0x40449B: unzip (unzip.c:1280)
==15725==    by 0x4874B26: (below main) (libc-start.c:308)
==15725==
   skipping: ??????????????????????????????????????????????????????????????????????????ı  need PK compat. v4.6 (can do v4.5)
==15725==
==15725== HEAP SUMMARY:
==15725==     in use at exit: 0 bytes in 0 blocks
==15725==   total heap usage: 37 allocs, 37 frees, 90,739 bytes allocated
==15725==
==15725== All heap blocks were freed -- no leaks are possible
==15725==
==15725== For counts of detected and suppressed errors, rerun with: -v
==15725== Use --track-origins=yes to see where uninitialised values come from
==15725== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

This is because wcstombs( newraw, wostring, (woslen * MB_CUR_MAX) + 1) in fnfilter
use wrong n parameter which stands for At most n bytes are written to dest.
When LANG environment variable is set, MB_CUR_MAX = 6, so wcstombs will writes more
bytes over dest(newraw).

Signed-off-by: Lv Ying <lvying6@huawei.com>
---
 extract.c | 4 ++--
 process.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/extract.c b/extract.c
index f0e8217..3f6e14d 100644
--- a/extract.c
+++ b/extract.c
@@ -2856,12 +2856,12 @@ char *fnfilter(raw, space, size)   /* convert name to safely printable form */
     if (wslen != (size_t)-1)
     {
         /* Apparently valid Unicode.  Allocate wide-char storage. */
-        wstring = (wchar_t *)malloc((wslen + 1) * sizeof(wchar_t));
+        wstring = (wchar_t *)calloc((wslen + 1), sizeof(wchar_t));
         if (wstring == NULL) {
             strcpy( (char *)space, raw);
             return (char *)space;
         }
-        wostring = (wchar_t *)malloc(2 * (wslen + 1) * sizeof(wchar_t));
+        wostring = (wchar_t *)calloc(2 * (wslen + 1), sizeof(wchar_t));
         if (wostring == NULL) {
             free(wstring);
             strcpy( (char *)space, raw);
diff --git a/process.c b/process.c
index 5cba073..3e7fcb3 100644
--- a/process.c
+++ b/process.c
@@ -2395,7 +2395,7 @@ char *local_to_utf8_string(local_string)
   */
 
  /* set this to the max bytes an escape can be */
-#define MAX_ESCAPE_BYTES 8
+#define MAX_ESCAPE_BYTES 10
 
 char *wide_to_escape_string(wide_char)
   zwchar wide_char;
-- 
2.27.0

