From b805d78d300bcf2c83d6df7da0c818b0fee41427 Mon Sep 17 00:00:00 2001 From: YueHaibing Date: Thu, 28 Feb 2019 15:18:59 +0800 Subject: xfrm: policy: Fix out-of-bound array accesses in __xfrm_policy_unlink UBSAN report this: UBSAN: Undefined behaviour in net/xfrm/xfrm_policy.c:1289:24 index 6 is out of range for type 'unsigned int [6]' CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.162-514.55.6.9.x86_64+ #13 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 0000000000000000 1466cf39b41b23c9 ffff8801f6b07a58 ffffffff81cb35f4 0000000041b58ab3 ffffffff83230f9c ffffffff81cb34e0 ffff8801f6b07a80 ffff8801f6b07a20 1466cf39b41b23c9 ffffffff851706e0 ffff8801f6b07ae8 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0x114/0x1a0 lib/dump_stack.c:51 [] ubsan_epilogue+0x12/0x8f lib/ubsan.c:164 [] __ubsan_handle_out_of_bounds+0x16e/0x1b2 lib/ubsan.c:382 [] __xfrm_policy_unlink+0x3dd/0x5b0 net/xfrm/xfrm_policy.c:1289 [] xfrm_policy_delete+0x52/0xb0 net/xfrm/xfrm_policy.c:1309 [] xfrm_policy_timer+0x30b/0x590 net/xfrm/xfrm_policy.c:243 [] call_timer_fn+0x237/0x990 kernel/time/timer.c:1144 [] __run_timers kernel/time/timer.c:1218 [inline] [] run_timer_softirq+0x6ce/0xb80 kernel/time/timer.c:1401 [] __do_softirq+0x299/0xe10 kernel/softirq.c:273 [] invoke_softirq kernel/softirq.c:350 [inline] [] irq_exit+0x216/0x2c0 kernel/softirq.c:391 [] exiting_irq arch/x86/include/asm/apic.h:652 [inline] [] smp_apic_timer_interrupt+0x8b/0xc0 arch/x86/kernel/apic/apic.c:926 [] apic_timer_interrupt+0xa5/0xb0 arch/x86/entry/entry_64.S:735 [] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:52 [] arch_safe_halt arch/x86/include/asm/paravirt.h:111 [inline] [] default_idle+0x27/0x430 arch/x86/kernel/process.c:446 [] arch_cpu_idle+0x15/0x20 arch/x86/kernel/process.c:437 [] default_idle_call+0x53/0x90 kernel/sched/idle.c:92 [] cpuidle_idle_call kernel/sched/idle.c:156 [inline] [] cpu_idle_loop kernel/sched/idle.c:251 [inline] [] cpu_startup_entry+0x60d/0x9a0 kernel/sched/idle.c:299 [] start_secondary+0x3c9/0x560 arch/x86/kernel/smpboot.c:245 The issue is triggered as this: xfrm_add_policy -->verify_newpolicy_info //check the index provided by user with XFRM_POLICY_MAX //In my case, the index is 0x6E6BB6, so it pass the check. -->xfrm_policy_construct //copy the user's policy and set xfrm_policy_timer -->xfrm_policy_insert --> __xfrm_policy_link //use the orgin dir, in my case is 2 --> xfrm_gen_index //generate policy index, there is 0x6E6BB6 then xfrm_policy_timer be fired xfrm_policy_timer --> xfrm_policy_id2dir //get dir from (policy index & 7), in my case is 6 --> xfrm_policy_delete --> __xfrm_policy_unlink //access policy_count[dir], trigger out of range access Add xfrm_policy_id2dir check in verify_newpolicy_info, make sure the computed dir is valid, to fix the issue. Reported-by: Hulk Robot Fixes: e682adf021be ("xfrm: Try to honor policy index if it's supplied by user") Signed-off-by: YueHaibing Acked-by: Herbert Xu Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_user.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net') diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index a131f9ff979e..8d4d52fd457b 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1424,7 +1424,7 @@ static int verify_newpolicy_info(struct xfrm_userpolicy_info *p) ret = verify_policy_dir(p->dir); if (ret) return ret; - if (p->index && ((p->index & XFRM_POLICY_MAX) != p->dir)) + if (p->index && (xfrm_policy_id2dir(p->index) != p->dir)) return -EINVAL; return 0; -- cgit v1.2.3-59-g8ed1b