From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: syzbot <syzbot+7a8ba368b47fdefca61e@syzkaller.appspotmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: debugfs: fix use-after-free on symlink traversal
Date: Tue, 26 Mar 2019 01:43:37 +0000 [thread overview]
Message-ID: <20190326014337.GX2217@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190326013858.GU2217@ZenIV.linux.org.uk>
symlink body shouldn't be freed without an RCU delay. Switch debugfs to
->destroy_inode() and use of call_rcu(); free both the inode and symlink
body in the callback. Similar to solution for bpf, only here it's even
more obvious that ->evict_inode() can be dropped.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 95b5e78c22b1..f25daa207421 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -163,19 +163,24 @@ static int debugfs_show_options(struct seq_file *m, struct dentry *root)
return 0;
}
-static void debugfs_evict_inode(struct inode *inode)
+static void debugfs_i_callback(struct rcu_head *head)
{
- truncate_inode_pages_final(&inode->i_data);
- clear_inode(inode);
+ struct inode *inode = container_of(head, struct inode, i_rcu);
if (S_ISLNK(inode->i_mode))
kfree(inode->i_link);
+ free_inode_nonrcu(inode);
+}
+
+static void debugfs_destroy_inode(struct inode *inode)
+{
+ call_rcu(&inode->i_rcu, debugfs_i_callback);
}
static const struct super_operations debugfs_super_operations = {
.statfs = simple_statfs,
.remount_fs = debugfs_remount,
.show_options = debugfs_show_options,
- .evict_inode = debugfs_evict_inode,
+ .destroy_inode = debugfs_destroy_inode,
};
static void debugfs_release_dentry(struct dentry *dentry)
next prev parent reply other threads:[~2019-03-26 1:43 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-28 17:40 KASAN: use-after-free Read in path_lookupat syzbot
2019-03-25 0:44 ` syzbot
2019-03-25 1:25 ` Linus Torvalds
2019-03-25 1:23 ` Linus Torvalds
2019-03-25 4:57 ` Al Viro
2019-03-25 9:15 ` Daniel Borkmann
2019-03-25 11:11 ` Al Viro
2019-03-25 11:17 ` Al Viro
2019-03-25 11:21 ` Daniel Borkmann
2019-03-25 18:36 ` Linus Torvalds
2019-03-25 19:18 ` Linus Torvalds
2019-03-25 21:14 ` Al Viro
2019-03-25 21:45 ` Linus Torvalds
2019-03-25 22:04 ` Daniel Borkmann
2019-03-25 22:13 ` Linus Torvalds
2019-03-25 22:41 ` Daniel Borkmann
2019-03-25 22:49 ` Al Viro
2019-03-25 23:37 ` Al Viro
2019-03-25 23:44 ` Alexei Starovoitov
2019-03-26 0:21 ` Al Viro
2019-03-26 1:38 ` ceph: fix use-after-free on symlink traversal Al Viro
2019-03-26 1:39 ` jffs2: " Al Viro
2019-03-26 1:40 ` ubifs: " Al Viro
2019-03-26 1:43 ` Al Viro [this message]
2019-03-26 10:41 ` ceph: " Jeff Layton
2019-03-26 11:38 ` Ilya Dryomov
2019-03-26 1:45 ` KASAN: use-after-free Read in path_lookupat Al Viro
2019-04-10 18:11 ` Al Viro
2019-04-10 19:44 ` Linus Torvalds
2019-03-25 19:43 ` Al Viro
2019-03-25 22:48 ` Dave Chinner
2019-03-25 23:02 ` Al Viro
[not found] ` <CAGe7X7mb=gK7zhSwmT_6mmmkcbjhZAOb=wj31BdUcHkNUPsm2Q@mail.gmail.com>
2019-03-26 4:15 ` Al Viro
2019-03-27 16:58 ` Jan Kara
2019-03-27 18:59 ` Al Viro
2019-03-28 9:00 ` Jan Kara
2019-03-27 17:22 ` Jan Kara
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