6.8-stable review patch. If anyone has any objections, please let me know.
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From: Jason A. Donenfeld Jason@zx2c4.com
[ Upstream commit 55b6c738673871c9b0edae05d0c97995c1ff08c4 ]
If all peers are removed via wg_peer_remove_all(), rather than setting peer_list to empty, the peer is added to a temporary list with a head on the stack of wg_peer_remove_all(). If a netlink dump is resumed and the cursored peer is one that has been removed via wg_peer_remove_all(), it will iterate from that peer and then attempt to dump freed peers.
Fix this by instead checking peer->is_dead, which was explictly created for this purpose. Also move up the device_update_lock lockdep assertion, since reading is_dead relies on that.
It can be reproduced by a small script like:
echo "Setting config..." ip link add dev wg0 type wireguard wg setconf wg0 /big-config ( while true; do echo "Showing config..." wg showconf wg0 > /dev/null done ) & sleep 4 wg setconf wg0 <(printf "[Peer]\nPublicKey=$(wg genkey)\n")
Resulting in:
BUG: KASAN: slab-use-after-free in __lock_acquire+0x182a/0x1b20 Read of size 8 at addr ffff88811956ec70 by task wg/59 CPU: 2 PID: 59 Comm: wg Not tainted 6.8.0-rc2-debug+ #5 Call Trace: <TASK> dump_stack_lvl+0x47/0x70 print_address_description.constprop.0+0x2c/0x380 print_report+0xab/0x250 kasan_report+0xba/0xf0 __lock_acquire+0x182a/0x1b20 lock_acquire+0x191/0x4b0 down_read+0x80/0x440 get_peer+0x140/0xcb0 wg_get_device_dump+0x471/0x1130
Cc: stable@vger.kernel.org Fixes: e7096c131e51 ("net: WireGuard secure network tunnel") Reported-by: Lillian Berry lillian@star-ark.net Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Reviewed-by: Jiri Pirko jiri@nvidia.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wireguard/netlink.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wireguard/netlink.c b/drivers/net/wireguard/netlink.c index e220d761b1f27..c17aee454fa3b 100644 --- a/drivers/net/wireguard/netlink.c +++ b/drivers/net/wireguard/netlink.c @@ -255,17 +255,17 @@ static int wg_get_device_dump(struct sk_buff *skb, struct netlink_callback *cb) if (!peers_nest) goto out; ret = 0; - /* If the last cursor was removed via list_del_init in peer_remove, then + lockdep_assert_held(&wg->device_update_lock); + /* If the last cursor was removed in peer_remove or peer_remove_all, then * we just treat this the same as there being no more peers left. The * reason is that seq_nr should indicate to userspace that this isn't a * coherent dump anyway, so they'll try again. */ if (list_empty(&wg->peer_list) || - (ctx->next_peer && list_empty(&ctx->next_peer->peer_list))) { + (ctx->next_peer && ctx->next_peer->is_dead)) { nla_nest_cancel(skb, peers_nest); goto out; } - lockdep_assert_held(&wg->device_update_lock); peer = list_prepare_entry(ctx->next_peer, &wg->peer_list, peer_list); list_for_each_entry_continue(peer, &wg->peer_list, peer_list) { if (get_peer(peer, skb, ctx)) {