On Wed, Nov 01, 2017 at 08:30:49PM +0100, Florian Westphal wrote: > syzbot reports: > BUG: KASAN: use-after-free in __xfrm_state_lookup+0x695/0x6b0 > Read of size 4 at addr ffff8801d434e538 by task syzkaller647520/2991 > [..] > __xfrm_state_lookup+0x695/0x6b0 net/xfrm/xfrm_state.c:833 > xfrm_state_lookup+0x8a/0x160 net/xfrm/xfrm_state.c:1592 > xfrm_input+0x8e5/0x22f0 net/xfrm/xfrm_input.c:302 > > The use-after-free is the ipv4 destination address, which points > to an skb head area that has been reallocated: > pskb_expand_head+0x36b/0x1210 net/core/skbuff.c:1494 > __pskb_pull_tail+0x14a/0x17c0 net/core/skbuff.c:1877 > pskb_may_pull include/linux/skbuff.h:2102 [inline] > xfrm_parse_spi+0x3d3/0x4d0 net/xfrm/xfrm_input.c:170 > xfrm_input+0xce2/0x22f0 net/xfrm/xfrm_input.c:291 > > so the real bug is that xfrm_parse_spi() uses pskb_may_pull, but > for now do smaller workaround that makes xfrm_input fetch daddr > after spi parsing. > > Reported-by: syzbot <syzkal...@googlegroups.com> > Signed-off-by: Florian Westphal <f...@strlen.de>
Applied, thanks Florian!
