From: Florian Westphal Date: Wed, 27 Dec 2017 22:25:45 +0000 (+0100) Subject: xfrm: skip policies marked as dead while rehashing X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=8e754b4ec589f14ef6efa454ee872580ba1802fa;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git xfrm: skip policies marked as dead while rehashing commit 862591bf4f519d1b8d859af720fafeaebdd0162a upstream. syzkaller triggered following KASAN splat: BUG: KASAN: slab-out-of-bounds in xfrm_hash_rebuild+0xdbe/0xf00 net/xfrm/xfrm_policy.c:618 read of size 2 at addr ffff8801c8e92fe4 by task kworker/1:1/23 [..] Workqueue: events xfrm_hash_rebuild [..] __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:428 xfrm_hash_rebuild+0xdbe/0xf00 net/xfrm/xfrm_policy.c:618 process_one_work+0xbbf/0x1b10 kernel/workqueue.c:2112 worker_thread+0x223/0x1990 kernel/workqueue.c:2246 [..] The reproducer triggers: 1016 if (error) { 1017 list_move_tail(&walk->walk.all, &x->all); 1018 goto out; 1019 } in xfrm_policy_walk() via pfkey (it sets tiny rcv space, dump callback returns -ENOBUFS). In this case, *walk is located the pfkey socket struct, so this socket becomes visible in the global policy list. It looks like this is intentional -- phony walker has walk.dead set to 1 and all other places skip such "policies". Ccing original authors of the two commits that seem to expose this issue (first patch missed ->dead check, second patch adds pfkey sockets to policies dumper list). Fixes: 880a6fab8f6ba5b ("xfrm: configure policy hash table thresholds by netlink") Fixes: 12a169e7d8f4b1c ("ipsec: Put dumpers on the dump list") Cc: Herbert Xu Cc: Timo Teras Cc: Christophe Gouault Reported-by: syzbot Signed-off-by: Florian Westphal Signed-off-by: Steffen Klassert Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 27b914000221..9dcfb7e080e1 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -610,7 +610,8 @@ static void xfrm_hash_rebuild(struct work_struct *work) /* re-insert all policies by order of creation */ list_for_each_entry_reverse(policy, &net->xfrm.policy_all, walk.all) { - if (xfrm_policy_id2dir(policy->index) >= XFRM_POLICY_MAX) { + if (policy->walk.dead || + xfrm_policy_id2dir(policy->index) >= XFRM_POLICY_MAX) { /* skip socket policies */ continue; }