linux-kernel - Re: [PATCH] Validate pointer when copying mount namespace.

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: <20150429023613.GM889@ZenIV.linux.org.uk>
Date:	Wed, 29 Apr 2015 03:36:13 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Leon Ma <xindong.ma@...el.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Validate pointer when copying mount namespace.

On Wed, Apr 29, 2015 at 09:56:43AM +0800, Leon Ma wrote:
> We encountered following panic. Validate the pointer to avoid this.

> @@ -2788,7 +2788,7 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
>  		q = next_mnt(q, new);
>  		if (!q)
>  			break;
> -		while (p->mnt.mnt_root != q->mnt.mnt_root)
> +		while (p && p->mnt.mnt_root != q->mnt.mnt_root)
>  			p = next_mnt(p, old);
>  	}
>  	namespace_unlock();

Details, please.  How do you reproduce that behaviour?  

I don't like that loop in its current form (it relies upon _not_ encountering
the same ->mnt_root in the parts of tree we hadn't copied), but your change
doesn't make it any better.  Seeing a reproducer would be useful in sorting
it out; in this form the patch papers over the bug rather than fixing it.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/