[PATCH] protect ext3 ioctl modifying append_only, immutable, etc. with i_mutex

All modifications of ->i_flags in inodes that might be visible to
somebody else must be under ->i_mutex.  That patch fixes ext3 ioctl()
setting S_APPEND and friends.

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

1 files changed, 14 insertions, 4 deletions

diff --git a/fs/ext3/ioctl.c b/fs/ext3/ioctl.c
index aaf1da17b6d4..8c22aa9a7fbb 100644
--- a/fs/ext3/ioctl.c
+++ b/fs/ext3/ioctl.c
@@ -48,6 +48,7 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
                 if (!S_ISDIR(inode->i_mode))
                         flags &= ~EXT3_DIRSYNC_FL;
 
+                mutex_lock(&inode->i_mutex);
                 oldflags = ei->i_flags;
 
                 /* The JOURNAL_DATA flag is modifiable only by root */
@@ -60,8 +61,10 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
                  * This test looks nicer. Thanks to Pauline Middelink
                  */
                 if ((flags ^ oldflags) & (EXT3_APPEND_FL | EXT3_IMMUTABLE_FL)) {
-                        if (!capable(CAP_LINUX_IMMUTABLE))
+                        if (!capable(CAP_LINUX_IMMUTABLE)) {
+                                mutex_unlock(&inode->i_mutex);
                                 return -EPERM;
+                        }
                 }
 
                 /*
@@ -69,14 +72,18 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
                  * the relevant capability.
                  */
                 if ((jflag ^ oldflags) & (EXT3_JOURNAL_DATA_FL)) {
-                        if (!capable(CAP_SYS_RESOURCE))
+                        if (!capable(CAP_SYS_RESOURCE)) {
+                                mutex_unlock(&inode->i_mutex);
                                 return -EPERM;
+                        }
                 }
 
 
                 handle = ext3_journal_start(inode, 1);
-                if (IS_ERR(handle))
+                if (IS_ERR(handle)) {
+                        mutex_unlock(&inode->i_mutex);
                         return PTR_ERR(handle);
+                }
                 if (IS_SYNC(inode))
                         handle->h_sync = 1;
                 err = ext3_reserve_inode_write(handle, inode, &iloc);
@@ -93,11 +100,14 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
                 err = ext3_mark_iloc_dirty(handle, inode, &iloc);
 flags_err:
                 ext3_journal_stop(handle);
-                if (err)
+                if (err) {
+                        mutex_unlock(&inode->i_mutex);
                         return err;
+                }
 
                 if ((jflag ^ oldflags) & (EXT3_JOURNAL_DATA_FL))
                         err = ext3_change_inode_journal_flag(inode, jflag);
+                mutex_unlock(&inode->i_mutex);
                 return err;
         }
         case EXT3_IOC_GETVERSION: