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Subject[PATCH 8/9] vfat: bug fix for vfat cannot handle filename with 255
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From: Keith Mok <ek9852@gmail.com>

This patch fix the problem that the buffer allocated for convert of
unicode to utf8 in fat/dir.c is too small.
And cannot handle filename with 255 asian characters when mounted with
utf8 options.

Also it fix the filename length limitation checking in vfat/namei.c that
the filename length should be checked against the number of converted
unicode characters.
Not the length before NLS/UTF8 converted.

Signed-off-by: Keith Mok <ek9852@gmail.com>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
---
fs/fat/dir.c | 44 ++++++++++++++++++++++++++++----------------
fs/vfat/namei.c | 25 +++++++++++--------------
2 files changed, 39 insertions(+), 30 deletions(-)
diff -puN fs/fat/dir.c~fat_vfat-fix-filename-handing fs/fat/dir.c
--- linux-2.6/fs/fat/dir.c~fat_vfat-fix-filename-handing 2008-04-19 11:55:08.000000000 +0900
+++ linux-2.6-hirofumi/fs/fat/dir.c 2008-04-21 00:59:00.000000000 +0900
@@ -124,8 +124,8 @@ static inline int fat_get_entry(struct i
* but ignore that right now.
* Ahem... Stack smashing in ring 0 isn't fun. Fixed.
*/
-static int uni16_to_x8(unsigned char *ascii, wchar_t *uni, int uni_xlate,
- struct nls_table *nls)
+static int uni16_to_x8(unsigned char *ascii, wchar_t *uni, int len,
+ int uni_xlate, struct nls_table *nls)
{
wchar_t *ip, ec;
unsigned char *op, nc;
@@ -135,10 +135,11 @@ static int uni16_to_x8(unsigned char *as
ip = uni;
op = ascii;

- while (*ip) {
+ while (*ip && ((len - NLS_MAX_CHARSET_SIZE) > 0)) {
ec = *ip++;
if ( (charlen = nls->uni2char(ec, op, NLS_MAX_CHARSET_SIZE)) > 0) {
op += charlen;
+ len -= charlen;
} else {
if (uni_xlate == 1) {
*op = ':';
@@ -149,16 +150,19 @@ static int uni16_to_x8(unsigned char *as
ec >>= 4;
}
op += 5;
+ len -= 5;
} else {
*op++ = '?';
+ len--;
}
}
- /* We have some slack there, so it's OK */
- if (op>ascii+256) {
- op = ascii + 256;
- break;
- }
}
+
+ if (unlikely(*ip)) {
+ printk(KERN_WARNING "FAT: filename was truncated while "
+ "converting.");
+ }
+
*op = 0;
return (op - ascii);
}
@@ -311,9 +315,11 @@ int fat_search_long(struct inode *inode,
struct nls_table *nls_io = sbi->nls_io;
struct nls_table *nls_disk = sbi->nls_disk;
wchar_t bufuname[14];
- unsigned char xlate_len, nr_slots;
+ unsigned char nr_slots;
+ int xlate_len;
wchar_t *unicode = NULL;
- unsigned char work[MSDOS_NAME], bufname[260]; /* 256 + 4 */
+ unsigned char work[MSDOS_NAME];
+ unsigned char *bufname = NULL;
int uni_xlate = sbi->options.unicode_xlate;
int utf8 = sbi->options.utf8;
int anycase = (sbi->options.name_check != 's');
@@ -321,6 +327,10 @@ int fat_search_long(struct inode *inode,
loff_t cpos = 0;
int chl, i, j, last_u, err;

+ bufname = (unsigned char*)__get_free_page(GFP_KERNEL);
+ if (!bufname)
+ return -ENOMEM;
+
err = -ENOENT;
while(1) {
if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
@@ -386,8 +396,8 @@ parse_record:

bufuname[last_u] = 0x0000;
xlate_len = utf8
- ?utf8_wcstombs(bufname, bufuname, sizeof(bufname))
- :uni16_to_x8(bufname, bufuname, uni_xlate, nls_io);
+ ?utf8_wcstombs(bufname, bufuname, PAGE_SIZE)
+ :uni16_to_x8(bufname, bufuname, PAGE_SIZE, uni_xlate, nls_io);
if (xlate_len == name_len)
if ((!anycase && !memcmp(name, bufname, xlate_len)) ||
(anycase && !nls_strnicmp(nls_io, name, bufname,
@@ -396,8 +406,8 @@ parse_record:

if (nr_slots) {
xlate_len = utf8
- ?utf8_wcstombs(bufname, unicode, sizeof(bufname))
- :uni16_to_x8(bufname, unicode, uni_xlate, nls_io);
+ ?utf8_wcstombs(bufname, unicode, PAGE_SIZE)
+ :uni16_to_x8(bufname, unicode, PAGE_SIZE, uni_xlate, nls_io);
if (xlate_len != name_len)
continue;
if ((!anycase && !memcmp(name, bufname, xlate_len)) ||
@@ -416,6 +426,8 @@ Found:
sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
err = 0;
EODir:
+ if (bufname)
+ free_page((unsigned long)bufname);
if (unicode)
free_page((unsigned long)unicode);

@@ -598,7 +610,7 @@ parse_record:
if (isvfat) {
bufuname[j] = 0x0000;
i = utf8 ? utf8_wcstombs(bufname, bufuname, sizeof(bufname))
- : uni16_to_x8(bufname, bufuname, uni_xlate, nls_io);
+ : uni16_to_x8(bufname, bufuname, sizeof(bufname), uni_xlate, nls_io);
}

fill_name = bufname;
@@ -610,7 +622,7 @@ parse_record:
int buf_size = PAGE_SIZE - (261 * sizeof(unicode[0]));
int long_len = utf8
? utf8_wcstombs(longname, unicode, buf_size)
- : uni16_to_x8(longname, unicode, uni_xlate, nls_io);
+ : uni16_to_x8(longname, unicode, buf_size, uni_xlate, nls_io);

if (!both) {
fill_name = longname;
diff -puN fs/vfat/namei.c~fat_vfat-fix-filename-handing fs/vfat/namei.c
--- linux-2.6/fs/vfat/namei.c~fat_vfat-fix-filename-handing 2008-04-19 11:55:08.000000000 +0900
+++ linux-2.6-hirofumi/fs/vfat/namei.c 2008-04-21 00:57:11.000000000 +0900
@@ -176,15 +176,10 @@ static inline int vfat_is_used_badchars(
for (i = 0; i < len; i++)
if (vfat_bad_char(s[i]))
return -EINVAL;
- return 0;
-}

-static int vfat_valid_longname(const unsigned char *name, unsigned int len)
-{
- if (name[len - 1] == ' ')
+ if (s[i - 1] == ' ') /* last character cannot be space */
return -EINVAL;
- if (len >= 256)
- return -ENAMETOOLONG;
+
return 0;
}

@@ -485,11 +480,14 @@ xlate_to_uni(const unsigned char *name,
*/
*outlen -= (name_len - len);

+ if (*outlen > 255)
+ return -ENAMETOOLONG;
+
op = &outname[*outlen * sizeof(wchar_t)];
} else {
if (nls) {
for (i = 0, ip = name, op = outname, *outlen = 0;
- i < len && *outlen <= 260;
+ i < len && *outlen <= 255;
*outlen += 1)
{
if (escape && (*ip == ':')) {
@@ -525,18 +523,20 @@ xlate_to_uni(const unsigned char *name,
op += 2;
}
}
+ if (i < len)
+ return -ENAMETOOLONG;
} else {
for (i = 0, ip = name, op = outname, *outlen = 0;
- i < len && *outlen <= 260;
+ i < len && *outlen <= 255;
i++, *outlen += 1)
{
*op++ = *ip++;
*op++ = 0;
}
+ if (i < len)
+ return -ENAMETOOLONG;
}
}
- if (*outlen > 260)
- return -ENAMETOOLONG;

*longlen = *outlen;
if (*outlen % 13) {
@@ -574,9 +574,6 @@ static int vfat_build_slots(struct inode
loff_t offset;

*nr_slots = 0;
- err = vfat_valid_longname(name, len);
- if (err)
- return err;

page = __get_free_page(GFP_KERNEL);
if (!page)
_

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