From: Christian Brauner <brauner@xxxxxxxxxx> commit 1bc6d44 upstream. Make it possible to quickly check whether AT_EMPTY_PATH is valid. Note, after some discussion we decided to also allow NULL to be passed instead of requiring the empty string. Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # 6.1.x Signed-off-by: Miao Wang <shankerwangmiao@xxxxxxxxx> Tested-by: Xi Ruoyao <xry111@xxxxxxxxxxx> --- include/linux/fs.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/linux/fs.h b/include/linux/fs.h index f2206c78755a..deb0abe728a7 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3692,4 +3692,21 @@ extern int vfs_fadvise(struct file *file, loff_t offset, loff_t len, extern int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice); +static inline bool vfs_empty_path(int dfd, const char __user *path) +{ + char c; + + if (dfd < 0) + return false; + + /* We now allow NULL to be used for empty path. */ + if (!path) + return true; + + if (unlikely(get_user(c, path))) + return false; + + return !c; +} + #endif /* _LINUX_FS_H */ -- 2.43.0