diff options
| author | Andreas Dilger <adilger@whamcloud.com> | 2011-10-26 09:22:31 +0200 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2011-10-26 09:22:31 +0200 |
| commit | 909a4cf1ffe4b875c87abf38239a9bfd25167e0c (patch) | |
| tree | f29e8150d7f4b840b1cc6cd143a3d957604116b9 /fs/ext4 | |
| parent | ext4: prevent stack overrun in ext4_file_open (diff) | |
| download | linux-909a4cf1ffe4b875c87abf38239a9bfd25167e0c.tar.xz linux-909a4cf1ffe4b875c87abf38239a9bfd25167e0c.zip | |
ext4: avoid setting directory i_nlink to zero
If a directory with more than EXT4_LINK_MAX subdirectories, the nlink
count is set to 1. Subsequently, if any subdirectories are deleted,
ext4_dec_count() decrements the i_nlink count, which may go to 0
temporarily before being incremented back to 1.
While this is done under i_mutex, which prevents races for directory
and inode operations that check i_nlink, the temporary i_nlink == 0
case is exposed to userspace via stat() and similar calls that do not
hold i_mutex.
Instead, change the code to not decrement i_nlink count for any
directories that do not already have i_nlink larger than 2.
Reported-by: Cliff White <cliffw@whamcloud.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/namei.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index a067835bbac1..4a550aa07614 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1706,9 +1706,8 @@ static void ext4_inc_count(handle_t *handle, struct inode *inode) */ static void ext4_dec_count(handle_t *handle, struct inode *inode) { - drop_nlink(inode); - if (S_ISDIR(inode->i_mode) && inode->i_nlink == 0) - inc_nlink(inode); + if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2) + drop_nlink(inode); } |