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Date: Sun, 13 Feb 2022 20:05:33 +0200
From: Ido Schimmel <idosch@...sch.org>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: "David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
netdev <netdev@...r.kernel.org>,
Eric Dumazet <edumazet@...gle.com>,
Mahesh Bandewar <maheshb@...gle.com>
Subject: Re: [PATCH net-next 2/4] ipv6: give an IPv6 dev to blackhole_netdev
On Thu, Feb 10, 2022 at 01:42:29PM -0800, Eric Dumazet wrote:
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 4f402bc38f056e08f3761e63a7bc7a51e54e9384..02d31d4fcab3b3d529c4fe3260216ecee1108e82 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -372,7 +372,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
>
> ASSERT_RTNL();
>
> - if (dev->mtu < IPV6_MIN_MTU)
> + if (dev->mtu < IPV6_MIN_MTU && dev != blackhole_netdev)
> return ERR_PTR(-EINVAL);
>
> ndev = kzalloc(sizeof(struct inet6_dev), GFP_KERNEL);
> @@ -400,21 +400,22 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
> /* We refer to the device */
> dev_hold_track(dev, &ndev->dev_tracker, GFP_KERNEL);
>
> - if (snmp6_alloc_dev(ndev) < 0) {
> - netdev_dbg(dev, "%s: cannot allocate memory for statistics\n",
> - __func__);
> - neigh_parms_release(&nd_tbl, ndev->nd_parms);
> - dev_put_track(dev, &ndev->dev_tracker);
> - kfree(ndev);
> - return ERR_PTR(err);
> - }
> + if (dev != blackhole_netdev) {
> + if (snmp6_alloc_dev(ndev) < 0) {
> + netdev_dbg(dev, "%s: cannot allocate memory for statistics\n",
> + __func__);
> + neigh_parms_release(&nd_tbl, ndev->nd_parms);
> + dev_put_track(dev, &ndev->dev_tracker);
> + kfree(ndev);
> + return ERR_PTR(err);
> + }
Hi,
Our regression machines crashed with the following splat [1]. Can be
reproduced with:
# ./fib_nexthops.sh -t ipv6_torture
>From tools/testing/selftests/net
Only had a couple of minutes (need to leave), but looks like the
following patch helps [2]. I can continue working on it tomorrow
morning, but wanted to mention it now in case you have a better idea /
someone else bumps into the same issue.
Thanks
[1]
[ 210.313674] ==================================================================
[ 210.314672] BUG: KASAN: null-ptr-deref in __ip6_make_skb+0x17fb/0x20a0
[ 210.315410] Write of size 8 at addr 0000000000000c00 by task ping/290
[ 210.316183]
[ 210.316359] CPU: 2 PID: 290 Comm: ping Not tainted 5.17.0-rc3-custom-02030-g17b65b552bb5 #1215
[ 210.317335] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1.fc35 04/01/2014
[ 210.318318] Call Trace:
[ 210.318618] <TASK>
[ 210.318876] dump_stack_lvl+0x8b/0xb3
[ 210.319803] kasan_report.cold+0x116/0x11b
[ 210.320876] kasan_check_range+0xf5/0x1d0
[ 210.321348] __ip6_make_skb+0x17fb/0x20a0
[ 210.323985] ip6_push_pending_frames+0xcd/0x110
[ 210.324628] rawv6_sendmsg+0x29f5/0x37f0
[ 210.329150] inet_sendmsg+0x9e/0xe0
[ 210.329596] __sys_sendto+0x23d/0x360
[ 210.333029] __x64_sys_sendto+0xe1/0x1b0
[ 210.334542] do_syscall_64+0x35/0x80
[ 210.334975] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 210.335632] RIP: 0033:0x7f2d8cd2f3aa
[ 210.336041] Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89
[ 210.338299] RSP: 002b:00007ffe1a5ec768 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
[ 210.339345] RAX: ffffffffffffffda RBX: 0000000000000038 RCX: 00007f2d8cd2f3aa
[ 210.340207] RDX: 0000000000000040 RSI: 00007f2d8cfbb320 RDI: 0000000000000004
[ 210.341284] RBP: 00007ffe1a5ec7f0 R08: 00007ffe1a5efee4 R09: 000000000000001c
[ 210.342212] R10: 0000000000000800 R11: 0000000000000246 R12: 00007f2d8cebb480
[ 210.343008] R13: 00007f2d8cea7f3d R14: 00007f2d8cea0c00 R15: 00007f2d8cebaa70
[ 210.343785] </TASK>
[ 210.344344] ==================================================================
(gdb) l *(__ip6_make_skb+0x17fb)
0xffffffff8389fb5b is in __ip6_make_skb (./arch/x86/include/asm/atomic64_64.h:88).
83 *
84 * Atomically increments @v by 1.
85 */
86 static __always_inline void arch_atomic64_inc(atomic64_t *v)
87 {
88 asm volatile(LOCK_PREFIX "incq %0"
89 : "=m" (v->counter)
90 : "m" (v->counter) : "memory");
91 }
92 #define arch_atomic64_inc arch_atomic64_inc
[2]
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 02d31d4fcab3..57fbd6f03ff8 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -400,16 +400,16 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
/* We refer to the device */
dev_hold_track(dev, &ndev->dev_tracker, GFP_KERNEL);
- if (dev != blackhole_netdev) {
- if (snmp6_alloc_dev(ndev) < 0) {
- netdev_dbg(dev, "%s: cannot allocate memory for statistics\n",
- __func__);
- neigh_parms_release(&nd_tbl, ndev->nd_parms);
- dev_put_track(dev, &ndev->dev_tracker);
- kfree(ndev);
- return ERR_PTR(err);
- }
+ if (snmp6_alloc_dev(ndev) < 0) {
+ netdev_dbg(dev, "%s: cannot allocate memory for statistics\n",
+ __func__);
+ neigh_parms_release(&nd_tbl, ndev->nd_parms);
+ dev_put_track(dev, &ndev->dev_tracker);
+ kfree(ndev);
+ return ERR_PTR(err);
+ }
+ if (dev != blackhole_netdev) {
if (snmp6_register_dev(ndev) < 0) {
netdev_dbg(dev, "%s: cannot create /proc/net/dev_snmp6/%s\n",
__func__, dev->name);
>
> - if (snmp6_register_dev(ndev) < 0) {
> - netdev_dbg(dev, "%s: cannot create /proc/net/dev_snmp6/%s\n",
> - __func__, dev->name);
> - goto err_release;
> + if (snmp6_register_dev(ndev) < 0) {
> + netdev_dbg(dev, "%s: cannot create /proc/net/dev_snmp6/%s\n",
> + __func__, dev->name);
> + goto err_release;
> + }
> }
> -
> /* One reference from device. */
> refcount_set(&ndev->refcnt, 1);
>
> @@ -445,25 +446,28 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
>
> ipv6_mc_init_dev(ndev);
> ndev->tstamp = jiffies;
> - err = addrconf_sysctl_register(ndev);
> - if (err) {
> - ipv6_mc_destroy_dev(ndev);
> - snmp6_unregister_dev(ndev);
> - goto err_release;
> + if (dev != blackhole_netdev) {
> + err = addrconf_sysctl_register(ndev);
> + if (err) {
> + ipv6_mc_destroy_dev(ndev);
> + snmp6_unregister_dev(ndev);
> + goto err_release;
> + }
> }
> /* protected by rtnl_lock */
> rcu_assign_pointer(dev->ip6_ptr, ndev);
>
> - /* Join interface-local all-node multicast group */
> - ipv6_dev_mc_inc(dev, &in6addr_interfacelocal_allnodes);
> + if (dev != blackhole_netdev) {
> + /* Join interface-local all-node multicast group */
> + ipv6_dev_mc_inc(dev, &in6addr_interfacelocal_allnodes);
>
> - /* Join all-node multicast group */
> - ipv6_dev_mc_inc(dev, &in6addr_linklocal_allnodes);
> -
> - /* Join all-router multicast group if forwarding is set */
> - if (ndev->cnf.forwarding && (dev->flags & IFF_MULTICAST))
> - ipv6_dev_mc_inc(dev, &in6addr_linklocal_allrouters);
> + /* Join all-node multicast group */
> + ipv6_dev_mc_inc(dev, &in6addr_linklocal_allnodes);
>
> + /* Join all-router multicast group if forwarding is set */
> + if (ndev->cnf.forwarding && (dev->flags & IFF_MULTICAST))
> + ipv6_dev_mc_inc(dev, &in6addr_linklocal_allrouters);
> + }
> return ndev;
>
> err_release:
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