should_follow_link(): validate ->d_seq after having decided to follow



... otherwise d_is_symlink() above might have nothing to do with
the inode value we've got.

Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent d4565649

fs/namei.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -1712,6 +1712,11 @@ static inline int should_follow_link(struct nameidata nd, struct path link,
		return 0;
		if (!follow)
		return 0;
		/* make sure that d_is_symlink above matches inode */
		if (nd->flags & LOOKUP_RCU) {
		if (read_seqcount_retry(&link->dentry->d_seq, seq))
		return -ECHILD;
		}
		return pick_link(nd, link, inode, seq);
		}