Subject: Re: [PATCH] xfrm_user: return error pointer instead of NULL

From: Steffen Klassert <[email-masked]>
Date: Mon, 17 Sep 2012 09:16:42 +0200

On Thu, Sep 13, 2012 at 11:41:26PM +0200, Mathias Krause wrote:
> When dump_one_state() returns an error, e.g. because of a too small
> buffer to dump the whole xfrm state, xfrm_state_netlink() returns NULL
> instead of an error pointer. But its callers expect an error pointer
> and therefore continue to operate on a NULL skbuff.
> 
> This could lead to a privilege escalation (execution of user code in
> kernel context) if the attacker has CAP_NET_ADMIN and is able to map
> address 0.

Or it simply crashes with a NULL pointer dereference.

> 
> Cc: [email-masked]
> Signed-off-by: Mathias Krause <[email-masked]>

Acked-by: Steffen Klassert <[email-masked]>