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