linux-kernel - [PATCH 3.2 27/79] eCryptfs: use after free in ecryptfs_release

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Message-ID: <lsq.1518322806.311122845@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:20:06 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Tyler Hicks" <tyhicks@...onical.com>,
        "Dan Carpenter" <dan.carpenter@...cle.com>
Subject: [PATCH 3.2 27/79] eCryptfs: use after free in ecryptfs_release_messaging()

3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@...cle.com>

commit db86be3a12d0b6e5c5b51c2ab2a48f06329cb590 upstream.

We're freeing the list iterator so we should be using the _safe()
version of hlist_for_each_entry().

Fixes: 88b4a07e6610 ("[PATCH] eCryptfs: Public key transport mechanism")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Tyler Hicks <tyhicks@...onical.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/fs/ecryptfs/messaging.c
+++ b/fs/ecryptfs/messaging.c
@@ -550,17 +550,17 @@ void ecryptfs_release_messaging(void)
 		mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
 	}
 	if (ecryptfs_daemon_hash) {
-		struct hlist_node *elem;
 		struct ecryptfs_daemon *daemon;
+		struct hlist_node *elem, *n;
 		int i;
 
 		mutex_lock(&ecryptfs_daemon_hash_mux);
 		for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
 			int rc;
 
-			hlist_for_each_entry(daemon, elem,
-					     &ecryptfs_daemon_hash[i],
-					     euid_chain) {
+			hlist_for_each_entry_safe(daemon, elem, n,
+						  &ecryptfs_daemon_hash[i],
+						  euid_chain) {
 				rc = ecryptfs_exorcise_daemon(daemon);
 				if (rc)
 					printk(KERN_ERR "%s: Error whilst "