From: Daniel Borkmann Date: Wed, 4 Nov 2015 22:33:17 +0000 (+0100) Subject: tracefs: Fix refcount imbalance in start_creating() X-Git-Tag: v4.4-rc1~85^2 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d227c3ae4e94e5eb11dd780a811f59e1a7b74ccd;p=karo-tx-linux.git 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 Signed-off-by: Steven Rostedt --- 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; }