KASAN: slab-out-of-bounds Read in fib6_add

Status: auto-obsoleted due to no activity on 2026/05/09 06:37
Reported-by: syzbot+6fca2b584268f3142fb2@syzkaller.appspotmail.com
First crash: 182d, last: 166d
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in fib6_add net 19 12 437d 449d 0/29 auto-obsoleted due to no activity on 2025/08/11 10:14
upstream KASAN: slab-use-after-free Write in fib6_add net 22 2 1013d 1014d 0/29 closed as invalid on 2023/12/13 08:55

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in fib6_add_rt2node net/ipv6/ip6_fib.c:1140 [inline]
BUG: KASAN: slab-out-of-bounds in fib6_add+0x4680/0x46e0 net/ipv6/ip6_fib.c:1503
Read of size 1 at addr ffff88805c442dce by task syz.7.2547/16346

CPU: 1 PID: 16346 Comm: syz.7.2547 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 fib6_add_rt2node net/ipv6/ip6_fib.c:1140 [inline]
 fib6_add+0x4680/0x46e0 net/ipv6/ip6_fib.c:1503
 __ip6_ins_rt net/ipv6/route.c:1352 [inline]
 ip6_route_add+0x8a/0x160 net/ipv6/route.c:3903
 inet6_rtm_newroute+0x2ba/0x1c90 net/ipv6/route.c:5567
 rtnetlink_rcv_msg+0x869/0xfa0 net/core/rtnetlink.c:6472
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
 __sys_sendmsg net/socket.c:2677 [inline]
 __do_sys_sendmsg net/socket.c:2686 [inline]
 __se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa36e59c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa36f4b5028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fa36e815fa0 RCX: 00007fa36e59c799
RDX: 0000000000000000 RSI: 0000200000000080 RDI: 0000000000000004
RBP: 00007fa36e632bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa36e816038 R14: 00007fa36e815fa0 R15: 00007ffecf47ee88
 </TASK>

Allocated by task 14743:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:198 [inline]
 __do_kmalloc_node mm/slab_common.c:1007 [inline]
 __kmalloc+0xb4/0x230 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 fib6_info_alloc+0x30/0xf0 net/ipv6/ip6_fib.c:155
 ip6_route_info_create+0x44f/0x1240 net/ipv6/route.c:3803
 ip6_route_add+0x28/0x160 net/ipv6/route.c:3899
 inet6_rtm_newroute+0x2ba/0x1c90 net/ipv6/route.c:5567
 rtnetlink_rcv_msg+0x869/0xfa0 net/core/rtnetlink.c:6472
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
 __sys_sendmsg net/socket.c:2677 [inline]
 __do_sys_sendmsg net/socket.c:2686 [inline]
 __se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
 insert_work+0x3d/0x310 kernel/workqueue.c:1651
 __queue_work+0xc39/0x1020 kernel/workqueue.c:1800
 queue_work_on+0x128/0x1f0 kernel/workqueue.c:1835
 queue_work include/linux/workqueue.h:562 [inline]
 call_usermodehelper_exec+0x284/0x4b0 kernel/umh.c:434
 call_modprobe kernel/module/kmod.c:103 [inline]
 __request_module+0x3dc/0x600 kernel/module/kmod.c:173
 dev_ioctl+0x79f/0x1140 net/core/dev_ioctl.c:768
 sock_do_ioctl+0x239/0x310 net/socket.c:1233
 sock_ioctl+0x5ba/0x7e0 net/socket.c:1340
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Second to last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
 insert_work+0x3d/0x310 kernel/workqueue.c:1651
 __queue_work+0xd2c/0x1020 kernel/workqueue.c:1804
 queue_work_on+0x128/0x1f0 kernel/workqueue.c:1835
 inet6addr_event+0xa0/0xd0 drivers/infiniband/core/roce_gid_mgmt.c:882
 notifier_call_chain+0x197/0x380 kernel/notifier.c:93
 atomic_notifier_call_chain+0xda/0x180 kernel/notifier.c:231
 ipv6_add_addr+0xdde/0x10d0 net/ipv6/addrconf.c:1189
 inet6_addr_add+0x57e/0xb60 net/ipv6/addrconf.c:3049
 inet6_rtm_newaddr+0x76f/0x9d0 net/ipv6/addrconf.c:5031
 rtnetlink_rcv_msg+0x869/0xfa0 net/core/rtnetlink.c:6472
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x4a9/0x6b0 net/socket.c:2200
 __do_sys_sendto net/socket.c:2212 [inline]
 __se_sys_sendto net/socket.c:2208 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2208
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88805c442d00
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 22 bytes to the right of
 allocated 184-byte region [ffff88805c442d00, ffff88805c442db8)

The buggy address belongs to the physical page:
page:ffffea0001711080 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5c442
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888017c41a00 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000001ffffffff 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 6833, tgid 6833 (cmp), ts 124294867693, free_ts 109518827815
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1581
 prep_new_page mm/page_alloc.c:1588 [inline]
 get_page_from_freelist+0x1951/0x19e0 mm/page_alloc.c:3220
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4486
 __alloc_pages_node include/linux/gfp.h:237 [inline]
 alloc_slab_page+0x4f/0x160 mm/slub.c:1883
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2081
 ___slab_alloc+0xc5d/0x12f0 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x19e/0x250 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node+0xa4/0x230 mm/slab_common.c:1014
 kmalloc_array_node include/linux/slab.h:698 [inline]
 kcalloc_node include/linux/slab.h:703 [inline]
 memcg_alloc_slab_cgroups+0x87/0x130 mm/memcontrol.c:2928
 account_slab mm/slab.h:641 [inline]
 allocate_slab mm/slub.c:2046 [inline]
 new_slab+0xc3/0x2d0 mm/slub.c:2081
 ___slab_alloc+0xc5d/0x12f0 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x1b3/0x2d0 mm/slub.c:3519
 vma_lock_alloc kernel/fork.c:460 [inline]
 vm_area_alloc+0x10e/0x1d0 kernel/fork.c:491
 __install_special_mapping+0x2f/0x320 mm/mmap.c:3602
 map_vdso+0x1a7/0x390 arch/x86/entry/vdso/vma.c:257
 load_elf_binary+0x1d0f/0x2860 fs/binfmt_elf.c:1308
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1181 [inline]
 free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2365
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2458
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x319/0x400 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 __kmem_cache_alloc_node+0x13a/0x250 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc+0xa4/0x230 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x282/0x560 security/tomoyo/file.c:822
 security_inode_getattr+0xd3/0x120 security/security.c:2153
 vfs_getattr fs/stat.c:173 [inline]
 vfs_fstat fs/stat.c:198 [inline]
 __do_sys_newfstat fs/stat.c:473 [inline]
 __se_sys_newfstat fs/stat.c:470 [inline]
 __x64_sys_newfstat+0x12c/0x250 fs/stat.c:470
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76

Memory state around the buggy address:
 ffff88805c442c80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805c442d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805c442d80: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
                                              ^
 ffff88805c442e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805c442e80: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (17):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/28 06:36 linux-6.6.y 7a137e9bfa0e 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/28 06:36 linux-6.6.y 7a137e9bfa0e 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/27 03:21 linux-6.6.y 7a137e9bfa0e a2f13f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/27 03:21 linux-6.6.y 7a137e9bfa0e a2f13f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/27 03:20 linux-6.6.y 7a137e9bfa0e a2f13f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/26 15:02 linux-6.6.y 7a137e9bfa0e ffa54287 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/26 03:29 linux-6.6.y 7a137e9bfa0e e0f78d93 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/24 02:23 linux-6.6.y 7a137e9bfa0e 41d2fa6a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/23 14:11 linux-6.6.y 7a137e9bfa0e 6beca497 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/23 14:11 linux-6.6.y 7a137e9bfa0e 6beca497 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/20 23:50 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/19 07:09 linux-6.6.y 56865d9b7074 746545b8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/19 07:08 linux-6.6.y 56865d9b7074 746545b8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/18 07:09 linux-6.6.y 56865d9b7074 39751c21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/17 19:24 linux-6.6.y 56865d9b7074 06ec4f7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/17 08:32 linux-6.6.y 56865d9b7074 e439b951 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
2026/02/11 18:34 linux-6.6.y 1b4ef5214f17 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in fib6_add
* Struck through repros no longer work on HEAD.