From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> commit dec9b2f1e0455a151a7293c367da22ab973f713e upstream. There is a very common pattern of using debugfs_remove(debufs_lookup(..)) which results in a dentry leak of the dentry that was looked up. Instead of having to open-code the correct pattern of calling dput() on the dentry, create debugfs_lookup_and_remove() to handle this pattern automatically and properly without any memory leaks. Cc: stable <stable@xxxxxxxxxx> Reported-by: Kuyo Chang <kuyo.chang@xxxxxxxxxxxx> Tested-by: Kuyo Chang <kuyo.chang@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/YxIaQ8cSinDR881k@xxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/debugfs/inode.c | 22 ++++++++++++++++++++++ include/linux/debugfs.h | 6 ++++++ 2 files changed, 28 insertions(+) --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -743,6 +743,28 @@ void debugfs_remove(struct dentry *dentr EXPORT_SYMBOL_GPL(debugfs_remove); /** + * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it + * @name: a pointer to a string containing the name of the item to look up. + * @parent: a pointer to the parent dentry of the item. + * + * This is the equlivant of doing something like + * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting + * handled for the directory being looked up. + */ +void debugfs_lookup_and_remove(const char *name, struct dentry *parent) +{ + struct dentry *dentry; + + dentry = debugfs_lookup(name, parent); + if (!dentry) + return; + + debugfs_remove(dentry); + dput(dentry); +} +EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove); + +/** * debugfs_remove_recursive - recursively removes a directory * @dentry: a pointer to a the dentry of the directory to be removed. If this * parameter is NULL or an error value, nothing will be done. --- a/include/linux/debugfs.h +++ b/include/linux/debugfs.h @@ -85,6 +85,8 @@ struct dentry *debugfs_create_automount( void debugfs_remove(struct dentry *dentry); void debugfs_remove_recursive(struct dentry *dentry); +void debugfs_lookup_and_remove(const char *name, struct dentry *parent); + const struct file_operations *debugfs_real_fops(const struct file *filp); int debugfs_file_get(struct dentry *dentry); @@ -216,6 +218,10 @@ static inline void debugfs_remove(struct static inline void debugfs_remove_recursive(struct dentry *dentry) { } +static inline void debugfs_lookup_and_remove(const char *name, + struct dentry *parent) +{ } + const struct file_operations *debugfs_real_fops(const struct file *filp); static inline int debugfs_file_get(struct dentry *dentry)
