This is a note to let you know that I've just added the patch titled
xfrm: skip policies marked as dead while rehashing
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: xfrm-skip-policies-marked-as-dead-while-rehashing.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 862591bf4f519d1b8d859af720fafeaebdd0162a Mon Sep 17 00:00:00 2001
From: Florian Westphal fw@strlen.de Date: Wed, 27 Dec 2017 23:25:45 +0100 Subject: xfrm: skip policies marked as dead while rehashing
From: Florian Westphal fw@strlen.de
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 herbert@gondor.apana.org.au Cc: Timo Teras timo.teras@iki.fi Cc: Christophe Gouault christophe.gouault@6wind.com Reported-by: syzbot bot+c028095236fcb6f4348811565b75084c754dc729@syzkaller.appspotmail.com Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/xfrm/xfrm_policy.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -643,7 +643,8 @@ static void xfrm_hash_rebuild(struct wor
/* 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; }
Patches currently in stable-queue which might be from fw@strlen.de are
queue-4.9/xfrm-skip-policies-marked-as-dead-while-rehashing.patch queue-4.9/netfilter-x_tables-avoid-out-of-bounds-reads-in-xt_request_find_-match-target.patch queue-4.9/netfilter-on-sockopt-acquire-sock-lock-only-in-the-required-scope.patch queue-4.9/netfilter-xt_rateest-acquire-xt_rateest_mutex-for-hash-insert.patch