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authorMing Lei <ming.lei@canonical.com>2013-03-20 23:25:24 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-03-20 16:53:42 -0700
commit991f76f837bf22c5bb07261cfd86525a0a96650c (patch)
treeaabd6397c35daee20d579507f4c5256e88e813ec
parenta937536b868b8369b98967929045f1df54234323 (diff)
downloadlinux-991f76f837bf22c5bb07261cfd86525a0a96650c.tar.bz2
sysfs: fix race between readdir and lseek
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> Cc: <stable@vger.kernel.org> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/sysfs/dir.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 2fbdff6be25c..c9e16608f486 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -1058,10 +1058,21 @@ 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_inode(file);
+ 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,
};