Matteo Croce <mcroce@xxxxxxxxxx> writes: > The FAT32 File System Specification[1] states that: > > If DIR_Name[0] == 0x00, then the directory entry is free, and there > are no allocated directory entries after this one. > > The special 0 value, indicates to FAT file system driver code that > the rest of the entries in this directory do not need to be examined > because they are all free. > > This is not enforced by Linux, and is possible to read garbage if not > all dirents after the last one are filled with zeroes. > > [1] http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/fatgen103.doc Tested some, and this patch seems to be not working. First fat_readdir() exits by zero dir entry, but dir pos is updated to next position, then second fat_readdir() continue with previous dir pos and will read beyond zero dir entry. So, maybe, we are better move down the zero dir entry handling into fat_get_entry(), instead of copying several places. But like you know, we would like to skip the zero dir entry only if read/search operation. Maybe, adding flag to fat_get_entry() and use it, or adding small wrapper? And in read/search case, we should not update *pos if hit the zero dir entry. I'm not testing the above actually though, we would need such. Thanks. > Reported-by: Timothy Redaelli <tredaelli@xxxxxxxxxx> > Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxx> > --- > fs/fat/dir.c | 20 ++++++++++++-------- > 1 file changed, 12 insertions(+), 8 deletions(-) > > diff --git a/fs/fat/dir.c b/fs/fat/dir.c > index 9d01db37183f..d919a1ee519c 100644 > --- a/fs/fat/dir.c > +++ b/fs/fat/dir.c > @@ -314,7 +314,7 @@ static int fat_parse_long(struct inode *dir, loff_t *pos, > > if (ds->id & 0x40) > (*unicode)[offset + 13] = 0; > - if (fat_get_entry(dir, pos, bh, de) < 0) > + if (fat_get_entry(dir, pos, bh, de) < 0 || !(*de)->name[0]) > return PARSE_EOF; > if (slot == 0) > break; > @@ -476,7 +476,8 @@ int fat_search_long(struct inode *inode, const unsigned char *name, > > err = -ENOENT; > while (1) { > - if (fat_get_entry(inode, &cpos, &bh, &de) == -1) > + if (fat_get_entry(inode, &cpos, &bh, &de) == -1 || > + !de->name[0]) > goto end_of_dir; > parse_record: > nr_slots = 0; > @@ -588,7 +589,7 @@ static int __fat_readdir(struct inode *inode, struct file *file, > > bh = NULL; > get_new: > - if (fat_get_entry(inode, &cpos, &bh, &de) == -1) > + if (fat_get_entry(inode, &cpos, &bh, &de) == -1 || !de->name[0]) > goto end_of_dir; > parse_record: > nr_slots = 0; > @@ -898,7 +899,8 @@ int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh, > loff_t offset = 0; > > *de = NULL; > - while (fat_get_short_entry(dir, &offset, bh, de) >= 0) { > + while (fat_get_short_entry(dir, &offset, bh, de) >= 0 && > + (*de)->name[0]) { > if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME)) > return 0; > } > @@ -916,7 +918,8 @@ int fat_dir_empty(struct inode *dir) > > bh = NULL; > cpos = 0; > - while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) { > + while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0 && > + de->name[0]) { > if (strncmp(de->name, MSDOS_DOT , MSDOS_NAME) && > strncmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) { > result = -ENOTEMPTY; > @@ -941,7 +944,8 @@ int fat_subdirs(struct inode *dir) > > bh = NULL; > cpos = 0; > - while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) { > + while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0 && > + de->name[0]) { > if (de->attr & ATTR_DIR) > count++; > } > @@ -961,7 +965,7 @@ int fat_scan(struct inode *dir, const unsigned char *name, > sinfo->slot_off = 0; > sinfo->bh = NULL; > while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh, > - &sinfo->de) >= 0) { > + &sinfo->de) >= 0 && sinfo->de->name[0]) { > if (!strncmp(sinfo->de->name, name, MSDOS_NAME)) { > sinfo->slot_off -= sizeof(*sinfo->de); > sinfo->nr_slots = 1; > @@ -985,7 +989,7 @@ int fat_scan_logstart(struct inode *dir, int i_logstart, > sinfo->slot_off = 0; > sinfo->bh = NULL; > while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh, > - &sinfo->de) >= 0) { > + &sinfo->de) >= 0 && sinfo->de->name[0]) { > if (fat_get_start(MSDOS_SB(sb), sinfo->de) == i_logstart) { > sinfo->slot_off -= sizeof(*sinfo->de); > sinfo->nr_slots = 1; -- OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
