ext{3,4}: Fix potential race when setversion ioctl updates inode

The EXT{3,4}_IOC_SETVERSION ioctl() updates i_ctime and i_generation
without i_mutex. This can lead to a race with the other operations that
update i_ctime. This is not a big issue but let's make the ioctl consistent
with how we handle e.g. other timestamp updates and use i_mutex to protect
inode changes.

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index a56796814d6a..46a8de6f2089 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -158,10 +158,11 @@ flags_out:
                         goto setversion_out;
                 }
 
+                mutex_lock(&inode->i_mutex);
                 handle = ext4_journal_start(inode, 1);
                 if (IS_ERR(handle)) {
                         err = PTR_ERR(handle);
-                        goto setversion_out;
+                        goto unlock_out;
                 }
                 err = ext4_reserve_inode_write(handle, inode, &iloc);
                 if (err == 0) {
@@ -170,6 +171,9 @@ flags_out:
                         err = ext4_mark_iloc_dirty(handle, inode, &iloc);
                 }
                 ext4_journal_stop(handle);
+
+unlock_out:
+                mutex_unlock(&inode->i_mutex);
 setversion_out:
                 mnt_drop_write(filp->f_path.mnt);
                 return err;