On Thu, Jul 27, 2017 at 11:22:04AM +0900, Taehee Yoo wrote: > If verdict is NF_STOLEN in the SYNPROXY target, > the skb is consumed. > However, ipt_do_table() always tries to get ip header from the skb. > So that, KASAN triggers the use-after-free message. > > We can reproduce this message using below command. > # iptables -I INPUT -p tcp -j SYNPROXY --mss 1460 > > [ 193.542265] BUG: KASAN: use-after-free in ipt_do_table+0x1405/0x1c10 > [ ... ] > [ 193.578603] Call Trace: > [ 193.581590] <IRQ> > [ 193.584107] dump_stack+0x68/0xa0 > [ 193.588168] print_address_description+0x78/0x290 > [ 193.593828] ? ipt_do_table+0x1405/0x1c10 > [ 193.598690] kasan_report+0x230/0x340 > [ 193.603194] __asan_report_load2_noabort+0x19/0x20 > [ 193.608950] ipt_do_table+0x1405/0x1c10 > [ 193.613591] ? rcu_read_lock_held+0xae/0xd0 > [ 193.618631] ? ip_route_input_rcu+0x27d7/0x4270 > [ 193.624348] ? ipt_do_table+0xb68/0x1c10 > [ 193.629124] ? do_add_counters+0x620/0x620 > [ 193.634234] ? iptable_filter_net_init+0x60/0x60 > [ ... ] > > After this patch, only when verdict is XT_CONTINUE, > ipt_do_table() tries to get ip header. > Also arpt_do_table() is modified because it has same bug. Applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
