diff options
| author | Ming Lei <ming.lei@canonical.com> | 2013-03-20 23:25:24 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-04-10 03:20:00 +0100 |
| commit | 76bfc5ab57137d351a9046a002ee39a220d0e012 (patch) | |
| tree | 517bde19947052216124976b423090e2347afc78 | |
| parent | 2c22dbb8ad3e320dfd1d98ba687b4966bcb65502 (diff) | |
sysfs: fix race between readdir and lseek
commit 991f76f837bf22c5bb07261cfd86525a0a96650c upstream.
While readdir() is running, lseek() may set filp->f_pos as zero,
then may leave filp->private_data pointing to one sysfs_dirent
object without holding its reference counter, so the sysfs_dirent
object may be used after free in next readdir().
This patch holds inode->i_mutex to avoid the problem since
the lock is always held in readdir path.
Reported-by: Dave Jones <davej@redhat.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: open-code file_inode() which we don't have]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | fs/sysfs/dir.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index fabbb81f5ce..309d21ad21f 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -1023,10 +1023,21 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) return 0; } +static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence) +{ + struct inode *inode = file->f_path.dentry->d_inode; + loff_t ret; + + mutex_lock(&inode->i_mutex); + ret = generic_file_llseek(file, offset, whence); + mutex_unlock(&inode->i_mutex); + + return ret; +} const struct file_operations sysfs_dir_operations = { .read = generic_read_dir, .readdir = sysfs_readdir, .release = sysfs_dir_release, - .llseek = generic_file_llseek, + .llseek = sysfs_dir_llseek, }; |