From: Florian Westphal <[email protected]>
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 <[email protected]>
Cc: Timo Teras <[email protected]>
Cc: Christophe Gouault <[email protected]>
Reported-by: syzbot
<bot+c028095236fcb6f4348811565b75084c754dc...@syzkaller.appspotmail.com>
Signed-off-by: Florian Westphal <[email protected]>
Signed-off-by: Steffen Klassert <[email protected]>
---
net/xfrm/xfrm_policy.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 70aa5cb0c659..2ef6db98e9ba 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -609,7 +609,8 @@ 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;
}
--
2.14.1
