From: Christian Brauner <brauner@kernel.org>
To: Edward Adam Davis <eadavis@qq.com>
Cc: syzbot+34a0ee986f61f15da35d@syzkaller.appspotmail.com,
jack@suse.cz, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
viro@zeniv.linux.org.uk
Subject: Re: [PATCH] fs/pidfs: when time ns disabled add check for ioctl
Date: Mon, 22 Jul 2024 10:00:58 +0200 [thread overview]
Message-ID: <20240722-graben-narren-76c25de0f0dd@brauner> (raw)
In-Reply-To: <tencent_7FAE8DB725EE0DD69236DDABDDDE195E4F07@qq.com>
On Sun, Jul 21, 2024 at 02:23:12PM GMT, Edward Adam Davis wrote:
> syzbot call pidfd_ioctl() with cmd "PIDFD_GET_TIME_NAMESPACE" and disabled
> CONFIG_TIME_NS, since time_ns is NULL, it will make NULL ponter deref in
> open_namespace.
>
> Reported-and-tested-by: syzbot+34a0ee986f61f15da35d@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=34a0ee986f61f15da35d
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
Hm, nsproxy is really messy in that regard. Some namespaces will always
be set to init_<type>_ns and others will be set to NULL.
That's an invitation for bugs such as this. Imho the correct fix is to
change nsproxy to always set nsp-><type>_ns to init_<type>_ns and no
code ever needs to worry about dereferencing NULL.
But that'll require more changes so this seems an appropriate fix for now.
next prev parent reply other threads:[~2024-07-22 8:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-20 16:36 [syzbot] [fs?] BUG: unable to handle kernel NULL pointer dereference in path_from_stashed syzbot
2024-07-21 4:50 ` Edward Adam Davis
2024-07-21 4:57 ` syzbot
2024-07-21 5:14 ` Edward Adam Davis
2024-07-21 5:41 ` syzbot
2024-07-21 6:23 ` [PATCH] fs/pidfs: when time ns disabled add check for ioctl Edward Adam Davis
2024-07-21 10:59 ` Matthew Wilcox
2024-07-22 8:00 ` Christian Brauner [this message]
2024-07-22 13:13 ` [PATCH 1/2] pidfs: handle kernels without namespaces cleanly Christian Brauner
2024-07-22 13:13 ` [PATCH 2/2] pidfs: add selftests for new namespace ioctls Christian Brauner
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