On Wed, Jan 09, 2019 at 02:37:34PM +0100, Florian Westphal wrote: > The check assumes that in transport mode, the first templates family > must match the address family of the policy selector. > > Syzkaller managed to build a template using MODE_ROUTEOPTIMIZATION, > with ipv4-in-ipv6 chain, leading to following splat: > > BUG: KASAN: stack-out-of-bounds in xfrm_state_find+0x1db/0x1854 > Read of size 4 at addr ffff888063e57aa0 by task a.out/2050 > xfrm_state_find+0x1db/0x1854 > xfrm_tmpl_resolve+0x100/0x1d0 > xfrm_resolve_and_create_bundle+0x108/0x1000 [..] > > Problem is that addresses point into flowi4 struct, but xfrm_state_find > treats them as being ipv6 because it uses templ->encap_family is used > (AF_INET6 in case of reproducer) rather than family (AF_INET). > > This patch inverts the logic: Enforce 'template family must match > selector' EXCEPT for tunnel and BEET mode. > > In BEET and Tunnel mode, xfrm_tmpl_resolve_one will have remote/local > address pointers changed to point at the addresses found in the template, > rather than the flowi ones, so no oob read will occur. > > Reported-by: [email protected] > Reported-by: Daniel Borkmann <[email protected]> > Signed-off-by: Florian Westphal <[email protected]>
Applied, thanks Florian!
