netdev - Re: [PATCH ipsec] xfrm: validate new SA's prefixlen using SA family when sel.family is unset

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Message-ID: <ZwY/3SegtYrbcSLd@gauss3.secunet.de>
Date: Wed, 9 Oct 2024 10:33:33 +0200
From: Steffen Klassert <steffen.klassert@...unet.com>
To: Sabrina Dubroca <sd@...asysnail.net>
CC: <netdev@...r.kernel.org>,
	<syzbot+cc39f136925517aed571@...kaller.appspotmail.com>
Subject: Re: [PATCH ipsec] xfrm: validate new SA's prefixlen using SA family
 when sel.family is unset

On Tue, Oct 01, 2024 at 06:48:14PM +0200, Sabrina Dubroca wrote:
> This expands the validation introduced in commit 07bf7908950a ("xfrm:
> Validate address prefix lengths in the xfrm selector.")
> 
> syzbot created an SA with
>     usersa.sel.family = AF_UNSPEC
>     usersa.sel.prefixlen_s = 128
>     usersa.family = AF_INET
> 
> Because of the AF_UNSPEC selector, verify_newsa_info doesn't put
> limits on prefixlen_{s,d}. But then copy_from_user_state sets
> x->sel.family to usersa.family (AF_INET). Do the same conversion in
> verify_newsa_info before validating prefixlen_{s,d}, since that's how
> prefixlen is going to be used later on.
> 
> Reported-by: syzbot+cc39f136925517aed571@...kaller.appspotmail.com
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>

Applied, thanks a lot Sabrina!