mm, hwpoison: fix possible use-after-free in mf_dax_kill_procs()

After kill_procs(), tk will be freed without being removed from the
to_kill list.  In the next iteration, the freed list entry in the to_kill
list will be accessed, thus leading to use-after-free issue.  Adding
list_del() in kill_procs() to fix the issue.

Link: https://lkml.kernel.org/r/20220823032346.4260-5-linmiaohe@huawei.com
Fixes: c36e20249571 ("mm: introduce mf_dax_kill_procs() for fsdax case")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 799176d..208a0f8 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -413,7 +413,7 @@ static void kill_procs(struct list_head *to_kill, int forcekill, bool fail,
 {
        struct to_kill *tk, *next;
 
-       list_for_each_entry_safe (tk, next, to_kill, nd) {
+       list_for_each_entry_safe(tk, next, to_kill, nd) {
                if (forcekill) {
                        /*
                         * In case something went wrong with munmapping
@@ -437,6 +437,7 @@ static void kill_procs(struct list_head *to_kill, int forcekill, bool fail,
                                pr_err("%#lx: Cannot send advisory machine check signal to %s:%d\n",
                                       pfn, tk->tsk->comm, tk->tsk->pid);
                }
+               list_del(&tk->nd);
                put_task_struct(tk->tsk);
                kfree(tk);
        }