| From 6d4cd25d28b8a6de834ea86bd7b1794e7fc09e1c Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 29 Mar 2021 12:12:54 -0700 |
| Subject: ip6_vti: proper dev_{hold|put} in ndo_[un]init methods |
| |
| From: Eric Dumazet <edumazet@google.com> |
| |
| [ Upstream commit 40cb881b5aaa0b69a7d93dec8440d5c62dae299f ] |
| |
| After adopting CONFIG_PCPU_DEV_REFCNT=n option, syzbot was able to trigger |
| a warning [1] |
| |
| Issue here is that: |
| |
| - all dev_put() should be paired with a corresponding prior dev_hold(). |
| |
| - A driver doing a dev_put() in its ndo_uninit() MUST also |
| do a dev_hold() in its ndo_init(), only when ndo_init() |
| is returning 0. |
| |
| Otherwise, register_netdevice() would call ndo_uninit() |
| in its error path and release a refcount too soon. |
| |
| Therefore, we need to move dev_hold() call from |
| vti6_tnl_create2() to vti6_dev_init_gen() |
| |
| [1] |
| WARNING: CPU: 0 PID: 15951 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31 |
| Modules linked in: |
| CPU: 0 PID: 15951 Comm: syz-executor.3 Not tainted 5.12.0-rc4-syzkaller #0 |
| Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 |
| RIP: 0010:refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31 |
| Code: 1d 6a 5a e8 09 31 ff 89 de e8 8d 1a ab fd 84 db 75 e0 e8 d4 13 ab fd 48 c7 c7 a0 e1 c1 89 c6 05 4a 5a e8 09 01 e8 2e 36 fb 04 <0f> 0b eb c4 e8 b8 13 ab fd 0f b6 1d 39 5a e8 09 31 ff 89 de e8 58 |
| RSP: 0018:ffffc90001eaef28 EFLAGS: 00010282 |
| RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 |
| RDX: 0000000000040000 RSI: ffffffff815c51f5 RDI: fffff520003d5dd7 |
| RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 |
| R10: ffffffff815bdf8e R11: 0000000000000000 R12: ffff88801bb1c568 |
| R13: ffff88801f69e800 R14: 00000000ffffffff R15: ffff888050889d40 |
| FS: 00007fc79314e700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| CR2: 00007f1c1ff47108 CR3: 0000000020fd5000 CR4: 00000000001506f0 |
| DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 |
| DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 |
| Call Trace: |
| __refcount_dec include/linux/refcount.h:344 [inline] |
| refcount_dec include/linux/refcount.h:359 [inline] |
| dev_put include/linux/netdevice.h:4135 [inline] |
| vti6_dev_uninit+0x31a/0x360 net/ipv6/ip6_vti.c:297 |
| register_netdevice+0xadf/0x1500 net/core/dev.c:10308 |
| vti6_tnl_create2+0x1b5/0x400 net/ipv6/ip6_vti.c:190 |
| vti6_newlink+0x9d/0xd0 net/ipv6/ip6_vti.c:1020 |
| __rtnl_newlink+0x1062/0x1710 net/core/rtnetlink.c:3443 |
| rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3491 |
| rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5553 |
| netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2502 |
| netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline] |
| netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338 |
| netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927 |
| sock_sendmsg_nosec net/socket.c:654 [inline] |
| sock_sendmsg+0xcf/0x120 net/socket.c:674 |
| ____sys_sendmsg+0x331/0x810 net/socket.c:2350 |
| ___sys_sendmsg+0xf3/0x170 net/socket.c:2404 |
| __sys_sendmmsg+0x195/0x470 net/socket.c:2490 |
| __do_sys_sendmmsg net/socket.c:2519 [inline] |
| __se_sys_sendmmsg net/socket.c:2516 [inline] |
| __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2516 |
| |
| Signed-off-by: Eric Dumazet <edumazet@google.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| net/ipv6/ip6_vti.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c |
| index ecfeffc06c55..82961ff4da9b 100644 |
| --- a/net/ipv6/ip6_vti.c |
| +++ b/net/ipv6/ip6_vti.c |
| @@ -192,7 +192,6 @@ static int vti6_tnl_create2(struct net_device *dev) |
| |
| strcpy(t->parms.name, dev->name); |
| |
| - dev_hold(dev); |
| vti6_tnl_link(ip6n, t); |
| |
| return 0; |
| @@ -931,6 +930,7 @@ static inline int vti6_dev_init_gen(struct net_device *dev) |
| dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats); |
| if (!dev->tstats) |
| return -ENOMEM; |
| + dev_hold(dev); |
| return 0; |
| } |
| |
| -- |
| 2.30.2 |
| |