vfat: bug fix for vfat cannot handle filename with 255

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 39 insertions, 30 deletions

diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 72cbcd61bd95..7b62ffb663f6 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -124,8 +124,8 @@ static inline int fat_get_entry(struct inode *dir, loff_t *pos,
  * 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 *ascii, wchar_t *uni, int uni_xlate,
         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 *ascii, wchar_t *uni, int uni_xlate,
                                         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, const unsigned char *name,
         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, const unsigned char *name,
         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 --git a/fs/vfat/namei.c b/fs/vfat/namei.c
index efc70576e4b4..ab4f3da770f0 100644
--- a/fs/vfat/namei.c
+++ b/fs/vfat/namei.c
@@ -176,15 +176,10 @@ static inline int vfat_is_used_badchars(const wchar_t *s, int len)
         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, int len, unsigned char *outname,
                  */
                 *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, int len, unsigned char *outname,
                                         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 *dir, const unsigned char *name,
         loff_t offset;
 
         *nr_slots = 0;
-        err = vfat_valid_longname(name, len);
-        if (err)
-                return err;
 
         page = __get_free_page(GFP_KERNEL);
         if (!page)