xfs: fix double free of inode
If we fail to initialise the VFS inode in inode_init_always(),
it will call ->delete_inode internally resulting in the inode being
freed. Hence we need to delay the call to inode_init_always()
until after the XFS inode is sufficient set up to handle a
call to ->delete_inode, and then if that fails do not touch
the inode again at all as it has been freed.
Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
index 478e587..89b81ee 100644
--- a/fs/xfs/xfs_iget.c
+++ b/fs/xfs/xfs_iget.c
@@ -69,15 +69,6 @@
ASSERT(!spin_is_locked(&ip->i_flags_lock));
ASSERT(completion_done(&ip->i_flush));
- /*
- * initialise the VFS inode here to get failures
- * out of the way early.
- */
- if (!inode_init_always(mp->m_super, VFS_I(ip))) {
- kmem_zone_free(xfs_inode_zone, ip);
- return NULL;
- }
-
/* initialise the xfs inode */
ip->i_ino = ino;
ip->i_mount = mp;
@@ -113,6 +104,20 @@
#ifdef XFS_DIR2_TRACE
ip->i_dir_trace = ktrace_alloc(XFS_DIR2_KTRACE_SIZE, KM_NOFS);
#endif
+ /*
+ * Now initialise the VFS inode. We do this after the xfs_inode
+ * initialisation as internal failures will result in ->destroy_inode
+ * being called and that will pass down through the reclaim path and
+ * free the XFS inode. This path requires the XFS inode to already be
+ * initialised. Hence if this call fails, the xfs_inode has already
+ * been freed and we should not reference it at all in the error
+ * handling.
+ */
+ if (!inode_init_always(mp->m_super, VFS_I(ip)))
+ return NULL;
+
+ /* prevent anyone from using this yet */
+ VFS_I(ip)->i_state = I_NEW|I_LOCK;
return ip;
}