From: Al Viro <viro@ZenIV.linux.org.uk>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: syzbot <syzbot+481ad819c717f6b78df9@syzkaller.appspotmail.com>,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
gregkh@linuxfoundation.org, tj@kernel.org
Subject: Re: general protection fault in kernfs_kill_sb (2)
Date: Mon, 14 May 2018 05:04:15 +0100 [thread overview]
Message-ID: <20180514040415.GD30522@ZenIV.linux.org.uk> (raw)
In-Reply-To: <201805140320.w4E3KG2o056158@www262.sakura.ne.jp>
On Mon, May 14, 2018 at 12:20:16PM +0900, Tetsuo Handa wrote:
> But there remains a refcount bug because deactivate_locked_super() from
> kernfs_mount_ns() triggers kobj_ns_drop() from sysfs_kill_sb() via
> sb->kill_sb() when kobj_ns_drop() is always called by sysfs_mount()
> if kernfs_mount_ns() returned an error.
Trivial:
unfuck sysfs_mount()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index b428d317ae92..92682fcc41f6 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -25,7 +25,7 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
{
struct dentry *root;
void *ns;
- bool new_sb;
+ bool new_sb = false;
if (!(flags & SB_KERNMOUNT)) {
if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
@@ -35,9 +35,9 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
root = kernfs_mount_ns(fs_type, flags, sysfs_root,
SYSFS_MAGIC, &new_sb, ns);
- if (IS_ERR(root) || !new_sb)
+ if (!new_sb)
kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
- else if (new_sb)
+ else if (!IS_ERR(root))
root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE;
return root;
next prev parent reply other threads:[~2018-05-14 4:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-12 17:01 general protection fault in kernfs_kill_sb (2) syzbot
2018-05-13 2:19 ` Tetsuo Handa
2018-05-14 2:47 ` Al Viro
[not found] ` <201805140320.w4E3KG2o056158@www262.sakura.ne.jp>
2018-05-14 4:04 ` Al Viro [this message]
2018-05-14 4:32 ` Al Viro
2018-05-15 0:17 ` Stephen Rothwell
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