linux/fs/hfs/trans.c
ZhangPeng c53ed55cb2 hfs: Fix OOB Write in hfs_asc2mac
Syzbot reported a OOB Write bug:

loop0: detected capacity change from 0 to 64
==================================================================
BUG: KASAN: slab-out-of-bounds in hfs_asc2mac+0x467/0x9a0
fs/hfs/trans.c:133
Write of size 1 at addr ffff88801848314e by task syz-executor391/3632

Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
 print_address_description+0x74/0x340 mm/kasan/report.c:284
 print_report+0x107/0x1f0 mm/kasan/report.c:395
 kasan_report+0xcd/0x100 mm/kasan/report.c:495
 hfs_asc2mac+0x467/0x9a0 fs/hfs/trans.c:133
 hfs_cat_build_key+0x92/0x170 fs/hfs/catalog.c:28
 hfs_lookup+0x1ab/0x2c0 fs/hfs/dir.c:31
 lookup_open fs/namei.c:3391 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0x10e6/0x2df0 fs/namei.c:3710
 do_filp_open+0x264/0x4f0 fs/namei.c:3740

If in->len is much larger than HFS_NAMELEN(31) which is the maximum
length of an HFS filename, a OOB write could occur in hfs_asc2mac(). In
that case, when the dst reaches the boundary, the srclen is still
greater than 0, which causes a OOB write.
Fix this by adding a check on dstlen in while() before writing to dst
address.

Link: https://lkml.kernel.org/r/20221202030038.1391945-1-zhangpeng362@huawei.com
Fixes: 328b922786 ("[PATCH] hfs: NLS support")
Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Reported-by: <syzbot+dc3b1cf9111ab5fe98e7@syzkaller.appspotmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-11 19:30:19 -08:00

151 lines
3.4 KiB
C

/*
* linux/fs/hfs/trans.c
*
* Copyright (C) 1995-1997 Paul H. Hargrove
* This file may be distributed under the terms of the GNU General Public License.
*
* This file contains routines for converting between the Macintosh
* character set and various other encodings. This includes dealing
* with ':' vs. '/' as the path-element separator.
*/
#include <linux/types.h>
#include <linux/nls.h>
#include "hfs_fs.h"
/*================ Global functions ================*/
/*
* hfs_mac2asc()
*
* Given a 'Pascal String' (a string preceded by a length byte) in
* the Macintosh character set produce the corresponding filename using
* the 'trivial' name-mangling scheme, returning the length of the
* mangled filename. Note that the output string is not NULL
* terminated.
*
* The name-mangling works as follows:
* The character '/', which is illegal in Linux filenames is replaced
* by ':' which never appears in HFS filenames. All other characters
* are passed unchanged from input to output.
*/
int hfs_mac2asc(struct super_block *sb, char *out, const struct hfs_name *in)
{
struct nls_table *nls_disk = HFS_SB(sb)->nls_disk;
struct nls_table *nls_io = HFS_SB(sb)->nls_io;
const char *src;
char *dst;
int srclen, dstlen, size;
src = in->name;
srclen = in->len;
if (srclen > HFS_NAMELEN)
srclen = HFS_NAMELEN;
dst = out;
dstlen = HFS_MAX_NAMELEN;
if (nls_io) {
wchar_t ch;
while (srclen > 0) {
if (nls_disk) {
size = nls_disk->char2uni(src, srclen, &ch);
if (size <= 0) {
ch = '?';
size = 1;
}
src += size;
srclen -= size;
} else {
ch = *src++;
srclen--;
}
if (ch == '/')
ch = ':';
size = nls_io->uni2char(ch, dst, dstlen);
if (size < 0) {
if (size == -ENAMETOOLONG)
goto out;
*dst = '?';
size = 1;
}
dst += size;
dstlen -= size;
}
} else {
char ch;
while (--srclen >= 0)
*dst++ = (ch = *src++) == '/' ? ':' : ch;
}
out:
return dst - out;
}
/*
* hfs_asc2mac()
*
* Given an ASCII string (not null-terminated) and its length,
* generate the corresponding filename in the Macintosh character set
* using the 'trivial' name-mangling scheme, returning the length of
* the mangled filename. Note that the output string is not NULL
* terminated.
*
* This routine is a inverse to hfs_mac2triv().
* A ':' is replaced by a '/'.
*/
void hfs_asc2mac(struct super_block *sb, struct hfs_name *out, const struct qstr *in)
{
struct nls_table *nls_disk = HFS_SB(sb)->nls_disk;
struct nls_table *nls_io = HFS_SB(sb)->nls_io;
const char *src;
char *dst;
int srclen, dstlen, size;
src = in->name;
srclen = in->len;
dst = out->name;
dstlen = HFS_NAMELEN;
if (nls_io) {
wchar_t ch;
while (srclen > 0 && dstlen > 0) {
size = nls_io->char2uni(src, srclen, &ch);
if (size < 0) {
ch = '?';
size = 1;
}
src += size;
srclen -= size;
if (ch == ':')
ch = '/';
if (nls_disk) {
size = nls_disk->uni2char(ch, dst, dstlen);
if (size < 0) {
if (size == -ENAMETOOLONG)
goto out;
*dst = '?';
size = 1;
}
dst += size;
dstlen -= size;
} else {
*dst++ = ch > 0xff ? '?' : ch;
dstlen--;
}
}
} else {
char ch;
if (dstlen > srclen)
dstlen = srclen;
while (--dstlen >= 0)
*dst++ = (ch = *src++) == ':' ? '/' : ch;
}
out:
out->len = dst - (char *)out->name;
dstlen = HFS_NAMELEN - out->len;
while (--dstlen >= 0)
*dst++ = 0;
}