blob: c739c4443ded1cf4bbf73b14dc2b1d93c4d2fd01 [file] [log] [blame]
From c0e3834816bbecae6718427e841b0c3e1cb7baf3 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Thu, 12 Mar 2020 18:25:20 -0400
Subject: [PATCH] cifs_atomic_open(): fix double-put on late allocation failure
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: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 3bd1148d8bb6..e816d68a7ff3 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -673,3 +673,8 @@ in your dentry operations instead.
d_alloc_pseudo() is internal-only; uses outside of alloc_file_pseudo() are
very suspect (and won't work in modules). Such uses are very likely to
be misspelled d_alloc_anon().
+--
+[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.
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 53b5bdf465e0..bf7644bf0605 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -561,7 +561,6 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
if (server->ops->close)
server->ops->close(xid, tcon, &fid);
cifs_del_pending_open(&open);
- fput(file);
rc = -ENOMEM;
}
diff --git a/fs/open.c b/fs/open.c
index a59abe3c669a..01c55f88b573 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -852,9 +852,6 @@ static int do_dentry_open(struct file *f,
* 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,
--
2.7.4