Messages in this thread | | | Date | Thu, 5 Nov 2015 08:30:31 -0500 | From | Steven Rostedt <> | Subject | Re: [for-next][PATCH] tracefs: Fix refcount imbalance in start_creating() |
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Forgot to Cc Daniel.
-- Steve
On Thu, 5 Nov 2015 08:29:33 -0500 Steven Rostedt <rostedt@goodmis.org> wrote:
> git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git > for-next > > Head SHA1: d227c3ae4e94e5eb11dd780a811f59e1a7b74ccd > > > Daniel Borkmann (1): > tracefs: Fix refcount imbalance in start_creating() > > ---- > fs/tracefs/inode.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > --------------------------- > commit d227c3ae4e94e5eb11dd780a811f59e1a7b74ccd > Author: Daniel Borkmann <daniel@iogearbox.net> > Date: Wed Nov 4 23:33:17 2015 +0100 > > tracefs: Fix refcount imbalance in start_creating() > > In tracefs' start_creating(), we pin the file system to safely access > its root. When we failed to create a file, we unpin the file system via > failed_creating() to release the mount count and eventually the reference > of the singleton vfsmount. > > However, when we run into an error during lookup_one_len() when still > in start_creating(), we only release the parent's mutex but not so the > reference on the mount. > > F.e., in securityfs_create_file(), after doing simple_pin_fs() when > lookup_one_len() fails there, we infact do simple_release_fs(). This > seems necessary here as well. > > Same issue seen in debugfs due to 190afd81e4a5 ("debugfs: split the > beginning and the end of __create_file() off"), which seemed to got > carried over into tracefs, too. Noticed during code review. > > Link: http://lkml.kernel.org/r/68efa86101b778cf7517ed7c6ad573bd69f60ec6.1446672850.git.daniel@iogearbox.net > > Fixes: 4282d60689d4 ("tracefs: Add new tracefs file system") > Cc: stable@vger.kernel.org # 4.1+ > Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org> > > diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c > index cbc8d5d2755a..c66f2423e1f5 100644 > --- a/fs/tracefs/inode.c > +++ b/fs/tracefs/inode.c > @@ -340,8 +340,12 @@ static struct dentry *start_creating(const char *name, struct dentry *parent) > dput(dentry); > dentry = ERR_PTR(-EEXIST); > } > - if (IS_ERR(dentry)) > + > + if (IS_ERR(dentry)) { > mutex_unlock(&parent->d_inode->i_mutex); > + simple_release_fs(&tracefs_mount, &tracefs_mount_count); > + } > + > return dentry; > } >
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