Re: [PATCH v2] ipsec: Fix aborted xfrm policy dump crash

[Steffen Klassert <steffen.klassert@secunet.com>]

On Thu, Oct 19, 2017 at 08:51:10PM +0800, Herbert Xu wrote:
> On Thu, Oct 19, 2017 at 02:33:20PM +0300, Timo Teras wrote:
> >
> > > Fixes: 4c563f7669c1 ("[XFRM]: Speed up xfrm_policy and xfrm_state...")
> > 
> > This is not correct. The original commit works just fine.
> 
> OK, I'll change it.
> 
> > At that time there was no .start which got added just few years ago. I
> > suggest to do the same fix for SA side since it had same issue fixed on
> > the other commit. Your approach with defining the .start is cleaner.
> 
> No we can't use the start on the SA side because as it is start
> is not allowed to fail.
> 
> Thanks,
> 
> ---8<---
> An independent security researcher, Mohamed Ghannam, has reported
> this vulnerability to Beyond Security's SecuriTeam Secure Disclosure
> program.
> 
> The xfrm_dump_policy_done function expects xfrm_dump_policy to
> have been called at least once or it will crash.  This can be
> triggered if a dump fails because the target socket's receive
> buffer is full.
> 
> This patch fixes it by using the cb->start mechanism to ensure that
> the initialisation is always done regardless of the buffer situation.
> 
> Fixes: 12a169e7d8f4 ("ipsec: Put dumpers on the dump list")
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Applied, thanks a lot Herbert!