syzbot


KASAN: slab-use-after-free Read in ovs_ct_exit

Status: fixed on 2024/05/23 19:09
Subsystems: openvswitch
[Documentation on labels]
Reported-by: syzbot+25f4f05818dda7aabaea@syzkaller.appspotmail.com
Fix commit: 5ea7b72d4fac net: openvswitch: Fix Use-After-Free in ovs_ct_exit
First crash: 263d, last: 233d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [openvswitch?] KASAN: slab-use-after-free Read in ovs_ct_exit 1 (2) 2024/05/19 13:42
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 KASAN: use-after-free Read in ovs_ct_exit 3 250d 323d 0/3 auto-obsoleted due to no activity on 2024/07/15 02:58
upstream KASAN: use-after-free Read in ovs_ct_exit (2) openvswitch 21 826d 1195d 0/28 auto-obsoleted due to no activity on 2023/01/05 07:06

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in ovs_ct_limit_exit net/openvswitch/conntrack.c:1597 [inline]
BUG: KASAN: slab-use-after-free in ovs_ct_exit+0x1f0/0x260 net/openvswitch/conntrack.c:1995
Read of size 8 at addr ffff88801e297680 by task kworker/u8:1/11

CPU: 1 PID: 11 Comm: kworker/u8:1 Not tainted 6.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:488
 kasan_report+0xd9/0x110 mm/kasan/report.c:601
 ovs_ct_limit_exit net/openvswitch/conntrack.c:1597 [inline]
 ovs_ct_exit+0x1f0/0x260 net/openvswitch/conntrack.c:1995
 ovs_exit_net+0xae/0x9b0 net/openvswitch/datapath.c:2680
 ops_exit_list+0xb0/0x180 net/core/net_namespace.c:170
 cleanup_net+0x5b7/0xbf0 net/core/net_namespace.c:637
 process_one_work+0x9a9/0x1ac0 kernel/workqueue.c:3254
 process_scheduled_works kernel/workqueue.c:3335 [inline]
 worker_thread+0x6c8/0xf70 kernel/workqueue.c:3416
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 12625:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:387
 kmalloc include/linux/slab.h:628 [inline]
 ovs_ct_limit_set_zone_limit net/openvswitch/conntrack.c:1660 [inline]
 ovs_ct_limit_cmd_set+0x30b/0xa90 net/openvswitch/conntrack.c:1837
 genl_family_rcv_msg_doit+0x202/0x2f0 net/netlink/genetlink.c:1113
 genl_family_rcv_msg net/netlink/genetlink.c:1193 [inline]
 genl_rcv_msg+0x565/0x800 net/netlink/genetlink.c:1208
 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2559
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1217
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0x542/0x820 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0xab5/0xc90 net/socket.c:2584
 ___sys_sendmsg+0x135/0x1e0 net/socket.c:2638
 __sys_sendmsg+0x117/0x1f0 net/socket.c:2667
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 11713:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
 poison_slab_object mm/kasan/common.c:240 [inline]
 __kasan_slab_free+0x11d/0x1a0 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2106 [inline]
 slab_free_freelist_hook mm/slub.c:2135 [inline]
 slab_free_bulk mm/slub.c:4293 [inline]
 kmem_cache_free_bulk mm/slub.c:4507 [inline]
 kmem_cache_free_bulk+0x155/0x390 mm/slub.c:4495
 kfree_bulk include/linux/slab.h:545 [inline]
 kvfree_rcu_bulk+0x454/0x550 kernel/rcu/tree.c:3033
 kvfree_rcu_drain_ready kernel/rcu/tree.c:3207 [inline]
 kfree_rcu_monitor+0x47b/0x12d0 kernel/rcu/tree.c:3225
 process_one_work+0x9a9/0x1ac0 kernel/workqueue.c:3254
 process_scheduled_works kernel/workqueue.c:3335 [inline]
 worker_thread+0x6c8/0xf70 kernel/workqueue.c:3416
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Last potentially related work creation:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xba/0xd0 mm/kasan/generic.c:541
 kvfree_call_rcu+0x74/0xbe0 kernel/rcu/tree.c:3443
 ovs_ct_limit_exit net/openvswitch/conntrack.c:1599 [inline]
 ovs_ct_exit+0x132/0x260 net/openvswitch/conntrack.c:1995
 ovs_exit_net+0xae/0x9b0 net/openvswitch/datapath.c:2680
 ops_exit_list+0xb0/0x180 net/core/net_namespace.c:170
 cleanup_net+0x5b7/0xbf0 net/core/net_namespace.c:637
 process_one_work+0x9a9/0x1ac0 kernel/workqueue.c:3254
 process_scheduled_works kernel/workqueue.c:3335 [inline]
 worker_thread+0x6c8/0xf70 kernel/workqueue.c:3416
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 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 ffff88801e297680
 which belongs to the cache kmalloc-cg-64 of size 64
The buggy address is located 0 bytes inside of
 freed 64-byte region [ffff88801e297680, ffff88801e2976c0)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88801e297180 pfn:0x1e297
memcg:ffff888029571801
anon flags: 0xfff80000000800(slab|node=0|zone=1|lastcpupid=0xfff)
page_type: 0xffffffff()
raw: 00fff80000000800 ffff88801504da00 ffffea00014f4d00 0000000000000005
raw: ffff88801e297180 000000000020001e 00000001ffffffff ffff888029571801
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 12449, tgid -980887775 (syz-executor.0), ts 12449, free_ts 703392532133
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x2d4/0x350 mm/page_alloc.c:1534
 prep_new_page mm/page_alloc.c:1541 [inline]
 get_page_from_freelist+0xa28/0x3780 mm/page_alloc.c:3317
 __alloc_pages+0x22b/0x2460 mm/page_alloc.c:4575
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 alloc_slab_page mm/slub.c:2175 [inline]
 allocate_slab mm/slub.c:2338 [inline]
 new_slab+0xcc/0x3a0 mm/slub.c:2391
 ___slab_alloc+0x66d/0x1790 mm/slub.c:3525
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3610
 __slab_alloc_node mm/slub.c:3663 [inline]
 slab_alloc_node mm/slub.c:3835 [inline]
 __do_kmalloc_node mm/slub.c:3965 [inline]
 __kmalloc_node+0x36e/0x480 mm/slub.c:3973
 kmalloc_node include/linux/slab.h:648 [inline]
 kvmalloc_node+0x9d/0x1a0 mm/util.c:634
 kvmalloc include/linux/slab.h:766 [inline]
 kvzalloc include/linux/slab.h:774 [inline]
 allocate_hook_entries_size net/netfilter/core.c:61 [inline]
 nf_hook_entries_grow+0x228/0x810 net/netfilter/core.c:140
 nf_hook_entries_insert_raw+0x3d/0x160 net/netfilter/core.c:204
 nf_nat_register_fn+0x1fc/0x5c0 net/netfilter/nf_nat_core.c:1145
 ip6t_nat_register_lookups net/ipv6/netfilter/ip6table_nat.c:79 [inline]
 ip6table_nat_table_init+0xf5/0x250 net/ipv6/netfilter/ip6table_nat.c:123
 xt_find_table_lock+0x2df/0x4f0 net/netfilter/x_tables.c:1260
 xt_request_find_table_lock+0x28/0xf0 net/netfilter/x_tables.c:1285
 get_info+0x19a/0x7c0 net/ipv4/netfilter/ip_tables.c:963
 do_ip6t_get_ctl+0x16a/0xaf0 net/ipv6/netfilter/ip6_tables.c:1668
page last free pid 12449 tgid 12449 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1141 [inline]
 free_unref_page_prepare+0x527/0xb10 mm/page_alloc.c:2347
 free_unref_page+0x33/0x3c0 mm/page_alloc.c:2487
 vfree+0x181/0x7a0 mm/vmalloc.c:3340
 copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:882 [inline]
 get_entries net/ipv6/netfilter/ip6_tables.c:1039 [inline]
 do_ip6t_get_ctl+0x8ec/0xaf0 net/ipv6/netfilter/ip6_tables.c:1677
 nf_getsockopt+0x79/0xe0 net/netfilter/nf_sockopt.c:116
 ipv6_getsockopt+0x1fd/0x2c0 net/ipv6/ipv6_sockglue.c:1494
 tcp_getsockopt+0x9e/0x100 net/ipv4/tcp.c:4375
 do_sock_getsockopt+0x2e5/0x760 net/socket.c:2373
 __sys_getsockopt+0x1a1/0x270 net/socket.c:2402
 __do_sys_getsockopt net/socket.c:2412 [inline]
 __se_sys_getsockopt net/socket.c:2409 [inline]
 __x64_sys_getsockopt+0xbd/0x160 net/socket.c:2409
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88801e297580: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88801e297600: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88801e297680: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff88801e297700: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88801e297780: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/22 14:37 upstream ed30a4a51bb1 af24b050 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in ovs_ct_exit
2024/04/20 14:01 upstream 13a2e429f644 af24b050 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce KASAN: slab-use-after-free Read in ovs_ct_exit
2024/03/25 02:59 upstream fe46a7dd189e 0ea90952 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in ovs_ct_exit
2024/03/23 20:41 upstream 480e035fc4c7 0ea90952 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce KASAN: slab-use-after-free Read in ovs_ct_exit
2024/03/27 14:20 net f99c5f563c17 454571b6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce KASAN: slab-use-after-free Read in ovs_ct_exit
2024/04/22 00:35 linux-next 7b4f2bc91c15 af24b050 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in ovs_ct_exit
* Struck through repros no longer work on HEAD.