[PATCH] vfat: bug fix for vfat cannot handle filename with 255 asiancharacters when mounted with utf8

From: Keith Mok
Date: Wed Feb 13 2008 - 11:55:31 EST


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.

Any comments ?


Signed-off-by: Keith Mok <ek9852@xxxxxxxxx>

---
Keith Mok




--- linux-source-2.6.22/fs/vfat/namei.c.orig 2007-07-09 07:32:17.000000000 +0800
+++ linux-source-2.6.22/fs/vfat/namei.c 2008-02-13 22:56:14.000000000 +0800
@@ -176,15 +176,8 @@ 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] == 0x0020) /* last character cannot be space */
return -EINVAL;
- if (len >= 256)
- return -ENAMETOOLONG;
return 0;
}

@@ -489,7 +482,7 @@ xlate_to_uni(const unsigned char *name, } 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 == ':')) {
@@ -527,7 +520,7 @@ xlate_to_uni(const unsigned char *name, }
} else {
for (i = 0, ip = name, op = outname, *outlen = 0;
- i < len && *outlen <= 260;
+ i < len && *outlen <= 255;
i++, *outlen += 1)
{
*op++ = *ip++;
@@ -535,7 +528,7 @@ xlate_to_uni(const unsigned char *name, }
}
}
- if (*outlen > 260)
+ if (*outlen > 255)
return -ENAMETOOLONG;

*longlen = *outlen;
@@ -574,9 +567,6 @@ 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)
--- linux-source-2.6.22/fs/fat/dir.c.orig 2007-07-09 07:32:17.000000000 +0800
+++ linux-source-2.6.22/fs/fat/dir.c 2008-02-14 00:42:52.000000000 +0800
@@ -124,7 +124,7 @@ 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,
+static int uni16_to_x8(unsigned char *ascii, wchar_t *uni, int len, int uni_xlate,
struct nls_table *nls)
{
wchar_t *ip, ec;
@@ -135,10 +135,13 @@ static int uni16_to_x8(unsigned char *as
ip = uni;
op = ascii;

- while (*ip) {
+ BUG_ON(len <= NLS_MAX_CHARSET_SIZE);
+
+ 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 = ':';
@@ -149,15 +152,18 @@ 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: truncated while convert unicode characters in %s\n",
+ __FUNCTION__);
}
*op = 0;
return (op - ascii);
@@ -311,9 +317,11 @@ 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;
+ int xlate_len;
+ unsigned char nr_slots;
wchar_t *unicode = NULL;
- unsigned char work[8], bufname[260]; /* 256 + 4 */
+ unsigned char work[8];
+ 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 +329,10 @@ 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)
@@ -383,8 +395,8 @@ 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,
@@ -393,8 +405,8 @@ 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)) ||
@@ -413,6 +425,8 @@ 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);

@@ -593,7 +607,7 @@ 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;
@@ -605,7 +619,7 @@ 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;


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