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> # 4.19.x-5.4.x
Signed-off-by: Miao Wang <shankerwangmiao@xxxxxxxxx>
Tested-by: Xi Ruoyao <xry111@xxxxxxxxxxx>
---
fs/stat.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/fs/stat.c b/fs/stat.c
index 526fa0801cad..3ae958308e48 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -150,6 +150,23 @@ int vfs_statx_fd(unsigned int fd, struct kstat *stat,
}
EXPORT_SYMBOL(vfs_statx_fd);
+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;
+}
+
/**
* vfs_statx - Get basic and extra attributes by filename
* @dfd: A file descriptor representing the base dir for a relative filename
--
2.43.0
