tree 11c18c7638bbeb0a09ee26cacd61f3a98ad893e8
parent 909e22e05353a783c526829427e9a8de122fba9c
author Pan Bian <bianpan2016@163.com> 1542959793 +0800
committer Al Viro <viro@zeniv.linux.org.uk> 1542982097 -0500

exportfs: do not read dentry after free

The function dentry_connected calls dput(dentry) to drop the previously
acquired reference to dentry. In this case, dentry can be released.
After that, IS_ROOT(dentry) checks the condition
(dentry == dentry->d_parent), which may result in a use-after-free bug.
This patch directly compares dentry with its parent obtained before
dropping the reference.

Fixes: a056cc8934c("exportfs: stop retrying once we race with
rename/remove")

Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>