linux-kernel - [PATCH AUTOSEL 3.18 05/10] jffs2: fix use-after-free on symlink traversal

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190424145259.31639-5-sashal@kernel.org>
Date:   Wed, 24 Apr 2019 10:52:54 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Al Viro <viro@...iv.linux.org.uk>, Sasha Levin <sashal@...nel.org>,
        linux-mtd@...ts.infradead.org
Subject: [PATCH AUTOSEL 3.18 05/10] jffs2: fix use-after-free on symlink traversal

From: Al Viro <viro@...iv.linux.org.uk>

[ Upstream commit 4fdcfab5b5537c21891e22e65996d4d0dd8ab4ca ]

free the symlink body after the same RCU delay we have for freeing the
struct inode itself, so that traversal during RCU pathwalk wouldn't step
into freed memory.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/jffs2/readinode.c | 5 -----
 fs/jffs2/super.c     | 5 ++++-
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c
index 386303dca382..4f390be71723 100644
--- a/fs/jffs2/readinode.c
+++ b/fs/jffs2/readinode.c
@@ -1429,11 +1429,6 @@ void jffs2_do_clear_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
 
 	jffs2_kill_fragtree(&f->fragtree, deleted?c:NULL);
 
-	if (f->target) {
-		kfree(f->target);
-		f->target = NULL;
-	}
-
 	fds = f->dents;
 	while(fds) {
 		fd = fds;
diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index 0bbc31d10857..d1be5991bb66 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c
@@ -47,7 +47,10 @@ static struct inode *jffs2_alloc_inode(struct super_block *sb)
 static void jffs2_i_callback(struct rcu_head *head)
 {
 	struct inode *inode = container_of(head, struct inode, i_rcu);
-	kmem_cache_free(jffs2_inode_cachep, JFFS2_INODE_INFO(inode));
+	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
+
+	kfree(f->target);
+	kmem_cache_free(jffs2_inode_cachep, f);
 }
 
 static void jffs2_destroy_inode(struct inode *inode)
-- 
2.19.1