[PATCH] protect ext2 ioctl modifying append_only immutable etc with i_mutex

Port commit a090d9132c1e53e3517111123680c15afb25c0a4 into ext2:

All modifications of ->i_flags in inodes that might be visible to somebody
else must be under ->i_mutex.  That patch fixes ext2 ioctl() setting S_APPEND.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/ext2/ioctl.c b/fs/ext2/ioctl.c
index 1dfba77eab10..e3cf8c81507f 100644
--- a/fs/ext2/ioctl.c
+++ b/fs/ext2/ioctl.c
@@ -44,6 +44,7 @@ int ext2_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
                 if (!S_ISDIR(inode->i_mode))
                         flags &= ~EXT2_DIRSYNC_FL;
 
+                mutex_lock(&inode->i_mutex);
                 oldflags = ei->i_flags;
 
                 /*
@@ -53,13 +54,16 @@ int ext2_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
                  * This test looks nicer. Thanks to Pauline Middelink
                  */
                 if ((flags ^ oldflags) & (EXT2_APPEND_FL | EXT2_IMMUTABLE_FL)) {
-                        if (!capable(CAP_LINUX_IMMUTABLE))
+                        if (!capable(CAP_LINUX_IMMUTABLE)) {
+                                mutex_unlock(&inode->i_mutex);
                                 return -EPERM;
+                        }
                 }
 
                 flags = flags & EXT2_FL_USER_MODIFIABLE;
                 flags |= oldflags & ~EXT2_FL_USER_MODIFIABLE;
                 ei->i_flags = flags;
+                mutex_unlock(&inode->i_mutex);
 
                 ext2_set_inode_flags(inode);
                 inode->i_ctime = CURRENT_TIME_SEC;