fat/nls: Fix handling of utf8 invalid char

With utf8 option, vfat allowed the duplicated filenames.

Normal nls returns -EINVAL for invalid char. But utf8s_to_utf16s()
skipped the invalid char historically.

So, this changes the utf8s_to_utf16s() directly to return -EINVAL for
invalid char, because vfat is only user of it.

mkdir /mnt/fatfs
FILENAME=`echo -ne "invalidutf8char_\\0341_endofchar"`
echo "Using filename: $FILENAME"
dd if=/dev/zero of=fatfs bs=512 count=128
mkdosfs -F 32 fatfs
mount -o loop,utf8 fatfs /mnt/fatfs
touch "/mnt/fatfs/$FILENAME"
umount /mnt/fatfs
mount -o loop,utf8 fatfs /mnt/fatfs
touch "/mnt/fatfs/$FILENAME"
ls -l /mnt/fatfs
umount /mnt/fatfs

----  And the output is:

Using filename: invalidutf8char_\0341_endofchar
128+0 records in
128+0 records out
65536 bytes (66 kB) copied, 0.000388118 s, 169 MB/s
mkdosfs 2.11 (12 Mar 2005)
total 0
-rwxr-xr-x 1 root root 0 Jun 28 19:46 invalidutf8char__endofchar
-rwxr-xr-x 1 root root 0 Jun 28 19:46 invalidutf8char__endofchar

Tested-by: Marton Balint <cus@fazekas.hu>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

2 files changed, 8 insertions, 15 deletions

diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index cb6e83557112..f565f24019b5 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -499,17 +499,10 @@ xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
         int charlen;
 
         if (utf8) {
-                int name_len = strlen(name);
-
-                *outlen = utf8s_to_utf16s(name, PATH_MAX, (wchar_t *) outname);
-
-                /*
-                 * We stripped '.'s before and set len appropriately,
-                 * but utf8s_to_utf16s doesn't care about len
-                 */
-                *outlen -= (name_len - len);
-
-                if (*outlen > 255)
+                *outlen = utf8s_to_utf16s(name, len, (wchar_t *)outname);
+                if (*outlen < 0)
+                        return *outlen;
+                else if (*outlen > 255)
                         return -ENAMETOOLONG;
 
                 op = &outname[*outlen * sizeof(wchar_t)];
diff --git a/fs/nls/nls_base.c b/fs/nls/nls_base.c
index 477d37d83b31..b25c218671b3 100644
--- a/fs/nls/nls_base.c
+++ b/fs/nls/nls_base.c
@@ -124,10 +124,10 @@ int utf8s_to_utf16s(const u8 *s, int len, wchar_t *pwcs)
         while (*s && len > 0) {
                 if (*s & 0x80) {
                         size = utf8_to_utf32(s, len, &u);
-                        if (size < 0) {
-                                /* Ignore character and move on */
-                                size = 1;
-                        } else if (u >= PLANE_SIZE) {
+                        if (size < 0)
+                                return -EINVAL;
+
+                        if (u >= PLANE_SIZE) {
                                 u -= PLANE_SIZE;
                                 *op++ = (wchar_t) (SURROGATE_PAIR |
                                                 ((u >> 10) & SURROGATE_BITS));