KASAN: slab-out-of-bounds Read in fib6_nh_get_excptn_bucket (3)

Status: auto-closed as invalid on 2021/09/13 13:28
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+f7687113afaeee05b412@syzkaller.appspotmail.com
First crash: 1967d, last: 1914d
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] KASAN: slab-out-of-bounds Read in fib6_nh_get_excptn_bucket (3) 0 (1) 2021/03/28 18:46
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-out-of-bounds Read in fib6_nh_get_excptn_bucket net 17 16 2389d 2521d 0/29 auto-closed as invalid on 2020/05/26 18:38
upstream KASAN: slab-out-of-bounds Read in fib6_nh_get_excptn_bucket (2) net 17 1 2078d 2078d 0/29 auto-closed as invalid on 2021/03/03 21:59
upstream general protection fault in fib6_nh_get_excptn_bucket net 2 1 427d 427d 0/29 closed as invalid on 2025/07/11 15:16
upstream general protection fault in fib6_nh_get_excptn_bucket (3) net 2 3 235d 260d 0/29 closed as invalid on 2026/02/18 04:33
upstream general protection fault in fib6_nh_get_excptn_bucket (2) net 2 1 338d 338d 0/29 closed as invalid on 2025/09/29 07:16
upstream general protection fault in fib6_nh_get_excptn_bucket (4) net 2 1 169d 169d 0/29 closed as invalid on 2026/04/08 13:02

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in fib6_nh_get_excptn_bucket+0x18b/0x1a0 net/ipv6/route.c:1604
Read of size 8 at addr ffff888014e760f8 by task swapper/2/0

CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.13.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2c6 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:436
 fib6_nh_get_excptn_bucket+0x18b/0x1a0 net/ipv6/route.c:1604
 fib6_nh_flush_exceptions+0x34/0x2d0 net/ipv6/route.c:1732
 fib6_nh_release+0x86/0x3f0 net/ipv6/route.c:3533
 fib6_info_destroy_rcu+0x187/0x210 net/ipv6/ip6_fib.c:174
 rcu_do_batch kernel/rcu/tree.c:2558 [inline]
 rcu_core+0x7ab/0x13b0 kernel/rcu/tree.c:2793
 __do_softirq+0x29b/0x9f6 kernel/softirq.c:559
 invoke_softirq kernel/softirq.c:433 [inline]
 __irq_exit_rcu+0x136/0x200 kernel/softirq.c:637
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:647
RIP: 0010:default_idle+0xe/0x10 arch/x86/kernel/process.c:701
Code: ff ff ff 48 89 df e8 f1 b6 9f f8 e9 52 ff ff ff 4c 89 e7 e8 e4 b6 9f f8 eb 93 66 90 e9 07 00 00 00 0f 00 2d e4 2b 4d 00 fb f4 <c3> cc 41 55 41 54 55 48 89 fd 53 e8 42 32 5b f8 e8 3d 59 fd ff 48
RSP: 0018:ffffc9000045fdf8 EFLAGS: 00000202
RAX: 0000000000298cc7 RBX: ffff888011c6a0c0 RCX: ffffffff89162431
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000002 R08: 0000000000000001 R09: ffff88802cc362cb
R10: ffffed1005986c59 R11: 0000000000000000 R12: ffffed100238d418
R13: 0000000000000002 R14: ffffffff8dc92ed0 R15: 0000000000000000
 default_idle_call+0x87/0xd0 kernel/sched/idle.c:112
 cpuidle_idle_call kernel/sched/idle.c:194 [inline]
 do_idle+0x401/0x590 kernel/sched/idle.c:306
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
 start_secondary+0x274/0x350 arch/x86/kernel/smpboot.c:272
 secondary_startup_64_no_verify+0xb0/0xbb

Allocated by task 27885:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:428 [inline]
 ____kasan_kmalloc mm/kasan/common.c:507 [inline]
 ____kasan_kmalloc mm/kasan/common.c:466 [inline]
 __kasan_kmalloc+0x98/0xc0 mm/kasan/common.c:516
 kasan_kmalloc include/linux/kasan.h:246 [inline]
 kmem_cache_alloc_trace+0x1fa/0x480 mm/slab.c:3575
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:686 [inline]
 fib6_info_alloc+0xbe/0x1d0 net/ipv6/ip6_fib.c:154
 ip6_route_info_create+0x33e/0x19d0 net/ipv6/route.c:3635
 ip6_route_add+0x24/0x150 net/ipv6/route.c:3725
 inet6_rtm_newroute+0x152/0x160 net/ipv6/route.c:5349
 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5562
 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+0x6e8/0x810 net/socket.c:2350
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xa4/0xd0 mm/kasan/generic.c:345
 __call_rcu kernel/rcu/tree.c:3038 [inline]
 call_rcu+0xb1/0x750 kernel/rcu/tree.c:3113
 fib6_info_release include/net/ip6_fib.h:337 [inline]
 fib6_info_release include/net/ip6_fib.h:334 [inline]
 ip6_route_info_create+0x125f/0x19d0 net/ipv6/route.c:3715
 ip6_route_add+0x24/0x150 net/ipv6/route.c:3725
 inet6_rtm_newroute+0x152/0x160 net/ipv6/route.c:5349
 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5562
 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+0x6e8/0x810 net/socket.c:2350
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Second to last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xa4/0xd0 mm/kasan/generic.c:345
 insert_work+0x48/0x370 kernel/workqueue.c:1331
 __queue_work+0x5c1/0xed0 kernel/workqueue.c:1497
 queue_work_on+0xee/0x110 kernel/workqueue.c:1524
 queue_work include/linux/workqueue.h:507 [inline]
 call_usermodehelper_exec+0x1f0/0x4c0 kernel/umh.c:435
 kobject_uevent_env+0xf95/0x1650 lib/kobject_uevent.c:618
 kvm_uevent_notify_change.part.0+0x326/0x460 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4963
 kvm_uevent_notify_change arch/x86/kvm/../../../virt/kvm/kvm_main.c:4922 [inline]
 kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:4249 [inline]
 kvm_dev_ioctl+0xc62/0x13a0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4271
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff888014e76000
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 56 bytes to the right of
 192-byte region [ffff888014e76000, ffff888014e760c0)
The buggy address belongs to the page:
page:ffffea0000539d80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14e76
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0000880548 ffffea000086f088 ffff888011040000
raw: 0000000000000000 ffff888014e76000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE), pid 1, ts 4997910385, free_ts 4955520938
 prep_new_page mm/page_alloc.c:2358 [inline]
 get_page_from_freelist+0x1033/0x2b60 mm/page_alloc.c:3994
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5200
 __alloc_pages_node include/linux/gfp.h:549 [inline]
 kmem_getpages mm/slab.c:1377 [inline]
 cache_grow_begin+0x75/0x460 mm/slab.c:2593
 cache_alloc_refill+0x27f/0x380 mm/slab.c:2965
 ____cache_alloc mm/slab.c:3048 [inline]
 ____cache_alloc mm/slab.c:3031 [inline]
 __do_cache_alloc mm/slab.c:3275 [inline]
 slab_alloc mm/slab.c:3316 [inline]
 kmem_cache_alloc_trace+0x3a2/0x480 mm/slab.c:3573
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:686 [inline]
 call_usermodehelper_setup+0x9a/0x300 kernel/umh.c:365
 kobject_uevent_env+0xf79/0x1650 lib/kobject_uevent.c:614
 kernel_add_sysfs_param kernel/params.c:798 [inline]
 param_sysfs_builtin kernel/params.c:833 [inline]
 param_sysfs_init+0x3bf/0x498 kernel/params.c:952
 do_one_initcall+0x103/0x650 init/main.c:1249
 do_initcall_level init/main.c:1322 [inline]
 do_initcalls init/main.c:1338 [inline]
 do_basic_setup init/main.c:1358 [inline]
 kernel_init_freeable+0x643/0x6cc init/main.c:1560
 kernel_init+0xd/0x1b8 init/main.c:1447
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1298 [inline]
 free_pcp_prepare+0x223/0x300 mm/page_alloc.c:1342
 free_unref_page_prepare mm/page_alloc.c:3250 [inline]
 free_unref_page+0x12/0x1d0 mm/page_alloc.c:3298
 rcu_do_batch kernel/rcu/tree.c:2558 [inline]
 rcu_core+0x7ab/0x13b0 kernel/rcu/tree.c:2793
 __do_softirq+0x29b/0x9f6 kernel/softirq.c:559
 invoke_softirq kernel/softirq.c:433 [inline]
 __irq_exit_rcu+0x136/0x200 kernel/softirq.c:637
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:647
 slab_alloc mm/slab.c:3318 [inline]
 kmem_cache_alloc+0x1a4/0x530 mm/slab.c:3507
 getname_kernel+0x4e/0x370 fs/namei.c:218
 kernel_execve+0x24/0x460 fs/exec.c:1936
 call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Memory state around the buggy address:
 ffff888014e75f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888014e76000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888014e76080: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
                                                                ^
 ffff888014e76100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888014e76180: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/05/16 13:28 upstream 63d1cb53e26a f54a5c09 .config console log report info ci-qemu-upstream KASAN: slab-out-of-bounds Read in fib6_nh_get_excptn_bucket
2021/03/24 15:31 upstream 7acac4b3196c 607e3baf .config console log report info ci-upstream-kasan-gce-root KASAN: slab-out-of-bounds Read in fib6_nh_get_excptn_bucket
* Struck through repros no longer work on HEAD.