chroot(2): import pathname only once

Convert the user_path_at() call inside a retry loop into getname_flags() +
filename_lookup() + putname() and leave only filename_lookup() inside
the loop.

In this case we never pass LOOKUP_EMPTY, so getname_flags() is equivalent
to plain getname().

The things could be further simplified by use of cleanup.h stuff, but
let's not clutter the patch with that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/open.c b/fs/open.c
index 67c114bdeac5..6f48fa9c756a 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -600,8 +600,9 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
 	struct path path;
 	int error;
 	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+	struct filename *name = getname(filename);
 retry:
-	error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
+	error = filename_lookup(AT_FDCWD, name, lookup_flags, &path, NULL);
 	if (error)
 		goto out;
 
@@ -625,6 +626,7 @@ dput_and_out:
 		goto retry;
 	}
 out:
+	putname(name);
 	return error;
 }