6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit 750e51603395e755537da08f745864c93e3ce741 ]
syzbot reported an UAF in default_operstate() [1]
Issue is a race between device and netns dismantles.
After calling __rtnl_unlock() from netdev_run_todo(), we can not assume the netns of each device is still alive.
Make sure the device is not in NETREG_UNREGISTERED state, and add an ASSERT_RTNL() before the call to __dev_get_by_index().
We might move this ASSERT_RTNL() in __dev_get_by_index() in the future.
[1]
BUG: KASAN: slab-use-after-free in __dev_get_by_index+0x5d/0x110 net/core/dev.c:852 Read of size 8 at addr ffff888043eba1b0 by task syz.0.0/5339
CPU: 0 UID: 0 PID: 5339 Comm: syz.0.0 Not tainted 6.12.0-syzkaller-10296-gaaf20f870da0 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x169/0x550 mm/kasan/report.c:489 kasan_report+0x143/0x180 mm/kasan/report.c:602 __dev_get_by_index+0x5d/0x110 net/core/dev.c:852 default_operstate net/core/link_watch.c:51 [inline] rfc2863_policy+0x224/0x300 net/core/link_watch.c:67 linkwatch_do_dev+0x3e/0x170 net/core/link_watch.c:170 netdev_run_todo+0x461/0x1000 net/core/dev.c:10894 rtnl_unlock net/core/rtnetlink.c:152 [inline] rtnl_net_unlock include/linux/rtnetlink.h:133 [inline] rtnl_dellink+0x760/0x8d0 net/core/rtnetlink.c:3520 rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6911 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2541 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1347 netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:726 ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2583 ___sys_sendmsg net/socket.c:2637 [inline] __sys_sendmsg+0x269/0x350 net/socket.c:2669 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2a3cb80809 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f2a3d9cd058 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f2a3cd45fa0 RCX: 00007f2a3cb80809 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000008 RBP: 00007f2a3cbf393e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f2a3cd45fa0 R15: 00007ffd03bc65c8 </TASK>
Allocated by task 5339: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4314 kmalloc_noprof include/linux/slab.h:901 [inline] kmalloc_array_noprof include/linux/slab.h:945 [inline] netdev_create_hash net/core/dev.c:11870 [inline] netdev_init+0x10c/0x250 net/core/dev.c:11890 ops_init+0x31e/0x590 net/core/net_namespace.c:138 setup_net+0x287/0x9e0 net/core/net_namespace.c:362 copy_net_ns+0x33f/0x570 net/core/net_namespace.c:500 create_new_namespaces+0x425/0x7b0 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x124/0x180 kernel/nsproxy.c:228 ksys_unshare+0x57d/0xa70 kernel/fork.c:3314 __do_sys_unshare kernel/fork.c:3385 [inline] __se_sys_unshare kernel/fork.c:3383 [inline] __x64_sys_unshare+0x38/0x40 kernel/fork.c:3383 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 12: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:582 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2338 [inline] slab_free mm/slub.c:4598 [inline] kfree+0x196/0x420 mm/slub.c:4746 netdev_exit+0x65/0xd0 net/core/dev.c:11992 ops_exit_list net/core/net_namespace.c:172 [inline] cleanup_net+0x802/0xcc0 net/core/net_namespace.c:632 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
The buggy address belongs to the object at ffff888043eba000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 432 bytes inside of freed 2048-byte region [ffff888043eba000, ffff888043eba800)
The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x43eb8 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 04fff00000000040 ffff88801ac42000 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000080008 00000001f5000000 0000000000000000 head: 04fff00000000040 ffff88801ac42000 dead000000000122 0000000000000000 head: 0000000000000000 0000000000080008 00000001f5000000 0000000000000000 head: 04fff00000000003 ffffea00010fae01 ffffffffffffffff 0000000000000000 head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5339, tgid 5338 (syz.0.0), ts 69674195892, free_ts 69663220888 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1556 prep_new_page mm/page_alloc.c:1564 [inline] get_page_from_freelist+0x3649/0x3790 mm/page_alloc.c:3474 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4751 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265 alloc_slab_page+0x6a/0x140 mm/slub.c:2408 allocate_slab+0x5a/0x2f0 mm/slub.c:2574 new_slab mm/slub.c:2627 [inline] ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3815 __slab_alloc+0x58/0xa0 mm/slub.c:3905 __slab_alloc_node mm/slub.c:3980 [inline] slab_alloc_node mm/slub.c:4141 [inline] __do_kmalloc_node mm/slub.c:4282 [inline] __kmalloc_noprof+0x2e6/0x4c0 mm/slub.c:4295 kmalloc_noprof include/linux/slab.h:905 [inline] sk_prot_alloc+0xe0/0x210 net/core/sock.c:2165 sk_alloc+0x38/0x370 net/core/sock.c:2218 __netlink_create+0x65/0x260 net/netlink/af_netlink.c:629 __netlink_kernel_create+0x174/0x6f0 net/netlink/af_netlink.c:2015 netlink_kernel_create include/linux/netlink.h:62 [inline] uevent_net_init+0xed/0x2d0 lib/kobject_uevent.c:783 ops_init+0x31e/0x590 net/core/net_namespace.c:138 setup_net+0x287/0x9e0 net/core/net_namespace.c:362 page last free pid 1032 tgid 1032 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1127 [inline] free_unref_page+0xdf9/0x1140 mm/page_alloc.c:2657 __slab_free+0x31b/0x3d0 mm/slub.c:4509 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4104 [inline] slab_alloc_node mm/slub.c:4153 [inline] kmem_cache_alloc_node_noprof+0x1d9/0x380 mm/slub.c:4205 __alloc_skb+0x1c3/0x440 net/core/skbuff.c:668 alloc_skb include/linux/skbuff.h:1323 [inline] alloc_skb_with_frags+0xc3/0x820 net/core/skbuff.c:6612 sock_alloc_send_pskb+0x91a/0xa60 net/core/sock.c:2881 sock_alloc_send_skb include/net/sock.h:1797 [inline] mld_newpack+0x1c3/0xaf0 net/ipv6/mcast.c:1747 add_grhead net/ipv6/mcast.c:1850 [inline] add_grec+0x1492/0x19a0 net/ipv6/mcast.c:1988 mld_send_initial_cr+0x228/0x4b0 net/ipv6/mcast.c:2234 ipv6_mc_dad_complete+0x88/0x490 net/ipv6/mcast.c:2245 addrconf_dad_completed+0x712/0xcd0 net/ipv6/addrconf.c:4342 addrconf_dad_work+0xdc2/0x16f0 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
Memory state around the buggy address: ffff888043eba080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888043eba100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888043eba180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff888043eba200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888043eba280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
Fixes: 8c55facecd7a ("net: linkwatch: only report IF_OPER_LOWERLAYERDOWN if iflink is actually down") Reported-by: syzbot+1939f24bdb783e9e43d9@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/674f3a18.050a0220.48a03.0041.GAE@google.com/T... Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Vladimir Oltean vladimir.oltean@nxp.com Link: https://patch.msgid.link/20241203170933.2449307-1-edumazet@google.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/link_watch.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/core/link_watch.c b/net/core/link_watch.c index ab150641142aa..1b4d39e380842 100644 --- a/net/core/link_watch.c +++ b/net/core/link_watch.c @@ -45,9 +45,14 @@ static unsigned int default_operstate(const struct net_device *dev) int iflink = dev_get_iflink(dev); struct net_device *peer;
- if (iflink == dev->ifindex) + /* If called from netdev_run_todo()/linkwatch_sync_dev(), + * dev_net(dev) can be already freed, and RTNL is not held. + */ + if (dev->reg_state == NETREG_UNREGISTERED || + iflink == dev->ifindex) return IF_OPER_DOWN;
+ ASSERT_RTNL(); peer = __dev_get_by_index(dev_net(dev), iflink); if (!peer) return IF_OPER_DOWN;