[PATCH] proc: reject "." and ".." as filenames

[Alexey Dobriyan]

Various subsystems can create files and directories in /proc
with names directly controlled by userspace.

Which means "/", "." and ".." are no-no.

"/" split is already taken care of, do the other 2 prohibited names.

Signed-off-by: Alexey Dobriyan <adobri...@gmail.com>
---

 fs/proc/generic.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -366,6 +366,14 @@ static struct proc_dir_entry *__proc_create(struct 
proc_dir_entry **parent,
                WARN(1, "name len %u\n", qstr.len);
                return NULL;
        }
+       if (qstr.len == 1 && fn[0] == '.') {
+               WARN(1, "name '.'\n");
+               return NULL;
+       }
+       if (qstr.len == 2 && fn[0] == '.' && fn[1] == '.') {
+               WARN(1, "name '..'\n");
+               return NULL;
+       }
        if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {
                WARN(1, "create '/proc/%s' by hand\n", qstr.name);
                return NULL;