Messages in this thread Patch in this message | | | From | Daniel Borkmann <> | Subject | [PATCH v2] tracefs: fix refcount imbalance in start_creating | Date | Wed, 4 Nov 2015 23:33:17 +0100 |
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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.
Fixes: 4282d60689d4 ("tracefs: Add new tracefs file system") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Steven Rostedt <rostedt@goodmis.org> --- v1 -> v2: - Split into two patches (tracefs and debugfs, will send debugfs one separately) - Kept Steven's Acked-by
fs/tracefs/inode.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index cbc8d5d..c66f242 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; } -- 1.9.3
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