ASR_BASE
Change-Id: Icf3719cc0afe3eeb3edc7fa80a2eb5199ca9dda1
diff --git a/target/linux/generic/backport-5.4/080-wireguard-0114-wireguard-noise-take-lock-when-removing-handshake-en.patch b/target/linux/generic/backport-5.4/080-wireguard-0114-wireguard-noise-take-lock-when-removing-handshake-en.patch
new file mode 100644
index 0000000..e80528c
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0114-wireguard-noise-take-lock-when-removing-handshake-en.patch
@@ -0,0 +1,127 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: "Jason A. Donenfeld" <Jason@zx2c4.com>
+Date: Wed, 9 Sep 2020 13:58:14 +0200
+Subject: [PATCH] wireguard: noise: take lock when removing handshake entry
+ from table
+
+commit 9179ba31367bcf481c3c79b5f028c94faad9f30a upstream.
+
+Eric reported that syzkaller found a race of this variety:
+
+CPU 1 CPU 2
+-------------------------------------------|---------------------------------------
+wg_index_hashtable_replace(old, ...) |
+ if (hlist_unhashed(&old->index_hash)) |
+ | wg_index_hashtable_remove(old)
+ | hlist_del_init_rcu(&old->index_hash)
+ | old->index_hash.pprev = NULL
+ hlist_replace_rcu(&old->index_hash, ...) |
+ *old->index_hash.pprev |
+
+Syzbot wasn't actually able to reproduce this more than once or create a
+reproducer, because the race window between checking "hlist_unhashed" and
+calling "hlist_replace_rcu" is just so small. Adding an mdelay(5) or
+similar there helps make this demonstrable using this simple script:
+
+ #!/bin/bash
+ set -ex
+ trap 'kill $pid1; kill $pid2; ip link del wg0; ip link del wg1' EXIT
+ ip link add wg0 type wireguard
+ ip link add wg1 type wireguard
+ wg set wg0 private-key <(wg genkey) listen-port 9999
+ wg set wg1 private-key <(wg genkey) peer $(wg show wg0 public-key) endpoint 127.0.0.1:9999 persistent-keepalive 1
+ wg set wg0 peer $(wg show wg1 public-key)
+ ip link set wg0 up
+ yes link set wg1 up | ip -force -batch - &
+ pid1=$!
+ yes link set wg1 down | ip -force -batch - &
+ pid2=$!
+ wait
+
+The fundumental underlying problem is that we permit calls to wg_index_
+hashtable_remove(handshake.entry) without requiring the caller to take
+the handshake mutex that is intended to protect members of handshake
+during mutations. This is consistently the case with calls to wg_index_
+hashtable_insert(handshake.entry) and wg_index_hashtable_replace(
+handshake.entry), but it's missing from a pertinent callsite of wg_
+index_hashtable_remove(handshake.entry). So, this patch makes sure that
+mutex is taken.
+
+The original code was a little bit funky though, in the form of:
+
+ remove(handshake.entry)
+ lock(), memzero(handshake.some_members), unlock()
+ remove(handshake.entry)
+
+The original intention of that double removal pattern outside the lock
+appears to be some attempt to prevent insertions that might happen while
+locks are dropped during expensive crypto operations, but actually, all
+callers of wg_index_hashtable_insert(handshake.entry) take the write
+lock and then explicitly check handshake.state, as they should, which
+the aforementioned memzero clears, which means an insertion should
+already be impossible. And regardless, the original intention was
+necessarily racy, since it wasn't guaranteed that something else would
+run after the unlock() instead of after the remove(). So, from a
+soundness perspective, it seems positive to remove what looks like a
+hack at best.
+
+The crash from both syzbot and from the script above is as follows:
+
+ general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
+ KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
+ CPU: 0 PID: 7395 Comm: kworker/0:3 Not tainted 5.9.0-rc4-syzkaller #0
+ Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
+ Workqueue: wg-kex-wg1 wg_packet_handshake_receive_worker
+ RIP: 0010:hlist_replace_rcu include/linux/rculist.h:505 [inline]
+ RIP: 0010:wg_index_hashtable_replace+0x176/0x330 drivers/net/wireguard/peerlookup.c:174
+ Code: 00 fc ff df 48 89 f9 48 c1 e9 03 80 3c 01 00 0f 85 44 01 00 00 48 b9 00 00 00 00 00 fc ff df 48 8b 45 10 48 89 c6 48 c1 ee 03 <80> 3c 0e 00 0f 85 06 01 00 00 48 85 d2 4c 89 28 74 47 e8 a3 4f b5
+ RSP: 0018:ffffc90006a97bf8 EFLAGS: 00010246
+ RAX: 0000000000000000 RBX: ffff888050ffc4f8 RCX: dffffc0000000000
+ RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88808e04e010
+ RBP: ffff88808e04e000 R08: 0000000000000001 R09: ffff8880543d0000
+ R10: ffffed100a87a000 R11: 000000000000016e R12: ffff8880543d0000
+ R13: ffff88808e04e008 R14: ffff888050ffc508 R15: ffff888050ffc500
+ FS: 0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
+ CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+ CR2: 00000000f5505db0 CR3: 0000000097cf7000 CR4: 00000000001526f0
+ DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+ DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+ Call Trace:
+ wg_noise_handshake_begin_session+0x752/0xc9a drivers/net/wireguard/noise.c:820
+ wg_receive_handshake_packet drivers/net/wireguard/receive.c:183 [inline]
+ wg_packet_handshake_receive_worker+0x33b/0x730 drivers/net/wireguard/receive.c:220
+ process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
+ worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
+ kthread+0x3b5/0x4a0 kernel/kthread.c:292
+ ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
+
+Reported-by: syzbot <syzkaller@googlegroups.com>
+Reported-by: Eric Dumazet <edumazet@google.com>
+Link: https://lore.kernel.org/wireguard/20200908145911.4090480-1-edumazet@google.com/
+Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+---
+ drivers/net/wireguard/noise.c | 5 +----
+ 1 file changed, 1 insertion(+), 4 deletions(-)
+
+--- a/drivers/net/wireguard/noise.c
++++ b/drivers/net/wireguard/noise.c
+@@ -87,15 +87,12 @@ static void handshake_zero(struct noise_
+
+ void wg_noise_handshake_clear(struct noise_handshake *handshake)
+ {
++ down_write(&handshake->lock);
+ wg_index_hashtable_remove(
+ handshake->entry.peer->device->index_hashtable,
+ &handshake->entry);
+- down_write(&handshake->lock);
+ handshake_zero(handshake);
+ up_write(&handshake->lock);
+- wg_index_hashtable_remove(
+- handshake->entry.peer->device->index_hashtable,
+- &handshake->entry);
+ }
+
+ static struct noise_keypair *keypair_create(struct wg_peer *peer)