[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>

diff --git a/fs/ext2/ioctl.c b/fs/ext2/ioctl.c
index 1dfba77eab10dc348e0ac3c4fa4e23d2448ac281..e3cf8c81507f64ef58c99a54c382e626051f1264 100644 (file)
--- 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;