Date:   Thu, 29 Jul 2021 16:33:58 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, Jiri Pirko <jiri@...dia.com>,
        Leon Romanovsky <leonro@...dia.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Parav Pandit <parav@...dia.com>
Subject: Re: [PATCH net-next v1 1/2] devlink: Break parameter notification
 sequence to be before/after unload/load driver

Thu, Jul 29, 2021 at 03:17:49PM CEST, leon@...nel.org wrote:
>From: Leon Romanovsky <leonro@...dia.com>
>
>The change of namespaces during devlink reload calls to driver unload
>before it accesses devlink parameters. The commands below causes to
>use-after-free bug when trying to get flow steering mode.
>
> * ip netns add n1
> * devlink dev reload pci/0000:00:09.0 netns n1
>
> ==================================================================
> BUG: KASAN: use-after-free in mlx5_devlink_fs_mode_get+0x96/0xa0 [mlx5_core]
> Read of size 4 at addr ffff888009d04308 by task devlink/275
>
> CPU: 6 PID: 275 Comm: devlink Not tainted 5.12.0-rc2+ #2853
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
> Call Trace:
>  dump_stack+0x93/0xc2
>  print_address_description.constprop.0+0x18/0x140
>  ? mlx5_devlink_fs_mode_get+0x96/0xa0 [mlx5_core]
>  ? mlx5_devlink_fs_mode_get+0x96/0xa0 [mlx5_core]
>  kasan_report.cold+0x7c/0xd8
>  ? mlx5_devlink_fs_mode_get+0x96/0xa0 [mlx5_core]
>  mlx5_devlink_fs_mode_get+0x96/0xa0 [mlx5_core]
>  devlink_nl_param_fill+0x1c8/0xe80
>  ? __free_pages_ok+0x37a/0x8a0
>  ? devlink_flash_update_timeout_notify+0xd0/0xd0
>  ? lock_acquire+0x1a9/0x6d0
>  ? fs_reclaim_acquire+0xb7/0x160
>  ? lock_is_held_type+0x98/0x110
>  ? 0xffffffff81000000
>  ? lock_release+0x1f9/0x6c0
>  ? fs_reclaim_release+0xa1/0xf0
>  ? lock_downgrade+0x6d0/0x6d0
>  ? lock_is_held_type+0x98/0x110
>  ? lock_is_held_type+0x98/0x110
>  ? memset+0x20/0x40
>  ? __build_skb_around+0x1f8/0x2b0
>  devlink_param_notify+0x6d/0x180
>  devlink_reload+0x1c3/0x520
>  ? devlink_remote_reload_actions_performed+0x30/0x30
>  ? mutex_trylock+0x24b/0x2d0
>  ? devlink_nl_cmd_reload+0x62b/0x1070
>  devlink_nl_cmd_reload+0x66d/0x1070
>  ? devlink_reload+0x520/0x520
>  ? devlink_get_from_attrs+0x1bc/0x260
>  ? devlink_nl_pre_doit+0x64/0x4d0
>  genl_family_rcv_msg_doit+0x1e9/0x2f0
>  ? mutex_lock_io_nested+0x1130/0x1130
>  ? genl_family_rcv_msg_attrs_parse.constprop.0+0x240/0x240
>  ? security_capable+0x51/0x90
>  genl_rcv_msg+0x27f/0x4a0
>  ? genl_get_cmd+0x3c0/0x3c0
>  ? lock_acquire+0x1a9/0x6d0
>  ? devlink_reload+0x520/0x520
>  ? lock_release+0x6c0/0x6c0
>  netlink_rcv_skb+0x11d/0x340
>  ? genl_get_cmd+0x3c0/0x3c0
>  ? netlink_ack+0x9f0/0x9f0
>  ? lock_release+0x1f9/0x6c0
>  genl_rcv+0x24/0x40
>  netlink_unicast+0x433/0x700
>  ? netlink_attachskb+0x730/0x730
>  ? _copy_from_iter_full+0x178/0x650
>  ? __alloc_skb+0x113/0x2b0
>  netlink_sendmsg+0x6f1/0xbd0
>  ? netlink_unicast+0x700/0x700
>  ? lock_is_held_type+0x98/0x110
>  ? netlink_unicast+0x700/0x700
>  sock_sendmsg+0xb0/0xe0
>  __sys_sendto+0x193/0x240
>  ? __x64_sys_getpeername+0xb0/0xb0
>  ? do_sys_openat2+0x10b/0x370
>  ? __up_read+0x1a1/0x7b0
>  ? do_user_addr_fault+0x219/0xdc0
>  ? __x64_sys_openat+0x120/0x1d0
>  ? __x64_sys_open+0x1a0/0x1a0
>  __x64_sys_sendto+0xdd/0x1b0
>  ? syscall_enter_from_user_mode+0x1d/0x50
>  do_syscall_64+0x2d/0x40
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7fc69d0af14a
> 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 76 c3 0f 1f 44 00 00 55 48 83 ec 30 44 89 4c
> RSP: 002b:00007ffc1d8292f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
> RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fc69d0af14a
> RDX: 0000000000000038 RSI: 0000555f57c56440 RDI: 0000000000000003
> RBP: 0000555f57c56410 R08: 00007fc69d17b200 R09: 000000000000000c
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>
> Allocated by task 146:
>  kasan_save_stack+0x1b/0x40
>  __kasan_kmalloc+0x99/0xc0
>  mlx5_init_fs+0xf0/0x1c50 [mlx5_core]
>  mlx5_load+0xd2/0x180 [mlx5_core]
>  mlx5_init_one+0x2f6/0x450 [mlx5_core]
>  probe_one+0x47d/0x6e0 [mlx5_core]
>  pci_device_probe+0x2a0/0x4a0
>  really_probe+0x20a/0xc90
>  driver_probe_device+0xd8/0x380
>  device_driver_attach+0x1df/0x250
>  __driver_attach+0xff/0x240
>  bus_for_each_dev+0x11e/0x1a0
>  bus_add_driver+0x309/0x570
>  driver_register+0x1ee/0x380
>  0xffffffffa06b8062
>  do_one_initcall+0xd5/0x410
>  do_init_module+0x1c8/0x760
>  load_module+0x6d8b/0x9650
>  __do_sys_finit_module+0x118/0x1b0
>  do_syscall_64+0x2d/0x40
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Freed by task 275:
>  kasan_save_stack+0x1b/0x40
>  kasan_set_track+0x1c/0x30
>  kasan_set_free_info+0x20/0x30
>  __kasan_slab_free+0x102/0x140
>  slab_free_freelist_hook+0x74/0x1b0
>  kfree+0xd7/0x2a0
>  mlx5_unload+0x16/0xb0 [mlx5_core]
>  mlx5_unload_one+0xae/0x120 [mlx5_core]
>  mlx5_devlink_reload_down+0x1bc/0x380 [mlx5_core]
>  devlink_reload+0x141/0x520
>  devlink_nl_cmd_reload+0x66d/0x1070
>  genl_family_rcv_msg_doit+0x1e9/0x2f0
>  genl_rcv_msg+0x27f/0x4a0
>  netlink_rcv_skb+0x11d/0x340
>  genl_rcv+0x24/0x40
>  netlink_unicast+0x433/0x700
>  netlink_sendmsg+0x6f1/0xbd0
>  sock_sendmsg+0xb0/0xe0
>  __sys_sendto+0x193/0x240
>  __x64_sys_sendto+0xdd/0x1b0
>  do_syscall_64+0x2d/0x40
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> The buggy address belongs to the object at ffff888009d04300
>  which belongs to the cache kmalloc-128 of size 128
> The buggy address is located 8 bytes inside of
>  128-byte region [ffff888009d04300, ffff888009d04380)
> The buggy address belongs to the page:
> page:0000000086a64ecc refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888009d04000 pfn:0x9d04
> head:0000000086a64ecc order:1 compound_mapcount:0
> flags: 0x4000000000010200(slab|head)
> raw: 4000000000010200 ffffea0000203980 0000000200000002 ffff8880050428c0
> raw: ffff888009d04000 000000008020001d 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff888009d04200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888009d04280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >ffff888009d04300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                       ^
>  ffff888009d04380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff888009d04400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>The right solution to devlink reload is to notify about deletion of
>parameters, unload driver, change net namespaces, load driver and notify
>about addition of parameters.
>
>Fixes: 070c63f20f6c ("net: devlink: allow to change namespaces during reload")
>Reviewed-by: Parav Pandit <parav@...dia.com>
>Signed-off-by: Leon Romanovsky <leonro@...dia.com>
>---
> net/core/devlink.c | 32 ++++++++++++++++++++------------
> 1 file changed, 20 insertions(+), 12 deletions(-)
>
>diff --git a/net/core/devlink.c b/net/core/devlink.c
>index b596a971b473..4385930b896f 100644
>--- a/net/core/devlink.c
>+++ b/net/core/devlink.c
>@@ -3801,8 +3801,9 @@ static void devlink_param_notify(struct devlink *devlink,
> 				 struct devlink_param_item *param_item,
> 				 enum devlink_command cmd);
> 
>-static void devlink_reload_netns_change(struct devlink *devlink,
>-					struct net *dest_net)
>+static void devlink_ns_change_notify(struct devlink *devlink,
>+				     struct net *dest_net, struct net *curr_net,
>+				     enum devlink_command cmd, bool new)

Drop the cmd and determine the DEVLINK_CMD_PARAM_NEW/DEL by "new" arg as
well. I thought I wrote that clearly in my previous review, but
apparently not, sorry about that.



> {
> 	struct devlink_param_item *param_item;
> 
>@@ -3812,17 +3813,17 @@ static void devlink_reload_netns_change(struct devlink *devlink,
> 	 * reload process so the notifications are generated separatelly.
> 	 */
> 
>-	list_for_each_entry(param_item, &devlink->param_list, list)
>-		devlink_param_notify(devlink, 0, param_item,
>-				     DEVLINK_CMD_PARAM_DEL);
>-	devlink_notify(devlink, DEVLINK_CMD_DEL);
>+	if (!dest_net || net_eq(dest_net, curr_net))
>+		return;
> 
>-	__devlink_net_set(devlink, dest_net);
>+	if (new)
>+		devlink_notify(devlink, DEVLINK_CMD_NEW);
> 
>-	devlink_notify(devlink, DEVLINK_CMD_NEW);
> 	list_for_each_entry(param_item, &devlink->param_list, list)
>-		devlink_param_notify(devlink, 0, param_item,
>-				     DEVLINK_CMD_PARAM_NEW);
>+		devlink_param_notify(devlink, 0, param_item, cmd);

Like this:
		devlink_param_notify(devlink, 0, param_item, new ?
				     DEVLINK_CMD_PARAM_NEW ?
				     DEVLINK_CMD_PARAM_DEL);

>+
>+	if (!new)
>+		devlink_notify(devlink, DEVLINK_CMD_DEL);
> }
> 
> static bool devlink_reload_supported(const struct devlink_ops *ops)
>@@ -3902,6 +3903,7 @@ static int devlink_reload(struct devlink *devlink, struct net *dest_net,
> 			  u32 *actions_performed, struct netlink_ext_ack *extack)
> {
> 	u32 remote_reload_stats[DEVLINK_RELOAD_STATS_ARRAY_SIZE];
>+	struct net *curr_net;
> 	int err;
> 
> 	if (!devlink->reload_enabled)
>@@ -3909,18 +3911,24 @@ static int devlink_reload(struct devlink *devlink, struct net *dest_net,
> 
> 	memcpy(remote_reload_stats, devlink->stats.remote_reload_stats,
> 	       sizeof(remote_reload_stats));
>+
>+	curr_net = devlink_net(devlink);
>+	devlink_ns_change_notify(devlink, dest_net, curr_net,
>+				 DEVLINK_CMD_PARAM_DEL, false);
> 	err = devlink->ops->reload_down(devlink, !!dest_net, action, limit, extack);
> 	if (err)
> 		return err;
> 
>-	if (dest_net && !net_eq(dest_net, devlink_net(devlink)))
>-		devlink_reload_netns_change(devlink, dest_net);
>+	if (dest_net && !net_eq(dest_net, curr_net))
>+		__devlink_net_set(devlink, dest_net);
> 
> 	err = devlink->ops->reload_up(devlink, action, limit, actions_performed, extack);
> 	devlink_reload_failed_set(devlink, !!err);
> 	if (err)
> 		return err;
> 
>+	devlink_ns_change_notify(devlink, dest_net, curr_net,
>+				 DEVLINK_CMD_PARAM_NEW, true);
> 	WARN_ON(!(*actions_performed & BIT(action)));
> 	/* Catch driver on updating the remote action within devlink reload */
> 	WARN_ON(memcmp(remote_reload_stats, devlink->stats.remote_reload_stats,
>-- 
>2.31.1
>

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