Messages in this thread Patch in this message | | | Date | Thu, 5 Nov 2015 08:29:33 -0500 | From | Steven Rostedt <> | Subject | [for-next][PATCH] tracefs: Fix refcount imbalance in start_creating() |
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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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