diff mbox series

[4.14,45/99] cifs_atomic_open(): fix double-put on late allocation failure

Message ID 20200319123955.571682852@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg KH March 19, 2020, 1:03 p.m. UTC 
From: Al Viro <viro@zeniv.linux.org.uk>

commit d9a9f4849fe0c9d560851ab22a85a666cddfdd24 upstream.

several iterations of ->atomic_open() calling conventions ago, we
used to need fput() if ->atomic_open() failed at some point after
successful finish_open().  Now (since 2016) it's not needed -
struct file carries enough state to make fput() work regardless
of the point in struct file lifecycle and discarding it on
failure exits in open() got unified.  Unfortunately, I'd missed
the fact that we had an instance of ->atomic_open() (cifs one)
that used to need that fput(), as well as the stale comment in
finish_open() demanding such late failure handling.  Trivially
fixed...

Fixes: fe9ec8291fca "do_last(): take fput() on error after opening to out:"
Cc: stable@kernel.org # v4.7+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 Documentation/filesystems/porting |    7 +++++++
 fs/cifs/dir.c                     |    1 -
 fs/open.c                         |    3 ---
 3 files changed, 7 insertions(+), 4 deletions(-)
diff mbox series

Patch

--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -606,3 +606,10 @@  in your dentry operations instead.
 	dentry separately, and it now has request_mask and query_flags arguments
 	to specify the fields and sync type requested by statx.  Filesystems not
 	supporting any statx-specific features may ignore the new arguments.
+--
+[mandatory]
+
+	[should've been added in 2016] stale comment in finish_open()
+	nonwithstanding, failure exits in ->atomic_open() instances should
+	*NOT* fput() the file, no matter what.  Everything is handled by the
+	caller.
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -562,7 +562,6 @@  cifs_atomic_open(struct inode *inode, st
 		if (server->ops->close)
 			server->ops->close(xid, tcon, &fid);
 		cifs_del_pending_open(&open);
-		fput(file);
 		rc = -ENOMEM;
 	}
 
--- a/fs/open.c
+++ b/fs/open.c
@@ -824,9 +824,6 @@  cleanup_file:
  * the return value of d_splice_alias(), then the caller needs to perform dput()
  * on it after finish_open().
  *
- * On successful return @file is a fully instantiated open file.  After this, if
- * an error occurs in ->atomic_open(), it needs to clean up with fput().
- *
  * Returns zero on success or -errno if the open failed.
  */
 int finish_open(struct file *file, struct dentry *dentry,