From 918ba24a9bbf85cbca33d2f3d5369915d3e7fbd3 Mon Sep 17 00:00:00 2001 From: Al Viro 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 Signed-off-by: Greg Kroah-Hartman --- Documentation/filesystems/porting.rst | 8 ++++++++ fs/cifs/dir.c | 1 - fs/open.c | 3 --- 3 files changed, 8 insertions(+), 4 deletions(-) diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst index f18506083ced..26c093969573 100644 --- a/Documentation/filesystems/porting.rst +++ b/Documentation/filesystems/porting.rst @@ -850,3 +850,11 @@ business doing so. 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 7ce689d31aa2..5a35850ccb1a 100644 --- a/fs/cifs/dir.c +++ b/fs/cifs/dir.c @@ -560,7 +560,6 @@ 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 b62f5c0923a8..dcbd01611237 100644 --- a/fs/open.c +++ b/fs/open.c @@ -860,9 +860,6 @@ 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,