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KASAN: slab-use-after-free Read in rose_t0timer_expiry

Status: upstream: reported on 2026/02/06 17:01
Subsystems: hams
[Documentation on labels]
Reported-by: syzbot+44cccec2c6a4501f6a45@syzkaller.appspotmail.com
First crash: 18d, last: 1d06h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [hams?] KASAN: slab-use-after-free Read in rose_t0timer_expiry 0 (1) 2026/02/06 17:01
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Write in rose_t0timer_expiry hams 22 2 124d 152d 0/29 auto-obsoleted due to no activity on 2026/02/01 07:03

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in rose_send_frame net/rose/rose_link.c:105 [inline]
BUG: KASAN: slab-use-after-free in rose_transmit_restart_request net/rose/rose_link.c:198 [inline]
BUG: KASAN: slab-use-after-free in rose_t0timer_expiry+0x1ea/0x560 net/rose/rose_link.c:83
Read of size 8 at addr ffff88806adc8c18 by task syz.0.1323/12926

CPU: 1 UID: 0 PID: 12926 Comm: syz.0.1323 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 rose_send_frame net/rose/rose_link.c:105 [inline]
 rose_transmit_restart_request net/rose/rose_link.c:198 [inline]
 rose_t0timer_expiry+0x1ea/0x560 net/rose/rose_link.c:83
 call_timer_fn+0x192/0x640 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2373 [inline]
 __run_timer_base+0x652/0x8b0 kernel/time/timer.c:2385
 run_timer_base kernel/time/timer.c:2394 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404
 handle_softirqs+0x22a/0x870 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:finish_task_switch+0x245/0x920 kernel/sched/core.c:5152
Code: 00 00 48 85 db 0f 85 e8 01 00 00 e9 56 05 00 00 4c 8b 75 d0 49 83 c4 48 4c 89 e7 e8 55 ce 1a 0a e8 50 7e 38 00 fb 4c 8b 65 c0 <49> 8d bc 24 30 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc900047976f8 EFLAGS: 00000206
RAX: 000000000000be71 RBX: 0000000000000000 RCX: 0000000080000001
RDX: 0000000000000007 RSI: ffffffff8def225c RDI: ffffffff8c27a880
RBP: ffffc90004797750 R08: ffffffff90117db7 R09: 1ffffffff2022fb6
R10: dffffc0000000000 R11: fffffbfff2022fb7 R12: ffff8880948fbc80
R13: dffffc0000000000 R14: ffff88802870bc80 R15: ffff8880b873b918
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0x158d/0x5340 kernel/sched/core.c:6907
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7091
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:389 [inline]
 follow_page_pte+0xced/0x1450 mm/gup.c:889
 follow_pmd_mask mm/gup.c:-1 [inline]
 follow_pud_mask mm/gup.c:967 [inline]
 follow_p4d_mask mm/gup.c:984 [inline]
 follow_page_mask mm/gup.c:1023 [inline]
 __get_user_pages+0xa77/0x29d0 mm/gup.c:1426
 populate_vma_page_range+0x2be/0x3c0 mm/gup.c:1860
 __mm_populate+0x25f/0x390 mm/gup.c:1963
 mm_populate include/linux/mm.h:3899 [inline]
 vm_mmap_pgoff+0x3aa/0x4f0 mm/util.c:586
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8fb1d9c629
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:00007f8fb2b8c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f8fb2016360 RCX: 00007f8fb1d9c629
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f8fb1e32b39 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8fb20163f8 R14: 00007f8fb2016360 R15: 00007fff900463b8
 </TASK>

Allocated by task 10956:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5339
 kmalloc_noprof include/linux/slab.h:962 [inline]
 rose_add_node+0x23c/0xf00 net/rose/rose_route.c:85
 rose_rt_ioctl+0xd35/0x12a0 net/rose/rose_route.c:748
 rose_ioctl+0x3fb/0x8f0 net/rose/af_rose.c:1382
 sock_do_ioctl+0x101/0x320 net/socket.c:1254
 sock_ioctl+0x5c6/0x7f0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 12895:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2687 [inline]
 slab_free mm/slub.c:6124 [inline]
 kfree+0x1c1/0x630 mm/slub.c:6442
 rose_neigh_put include/net/rose.h:166 [inline]
 rose_timer_expiry+0x4cb/0x600 net/rose/rose_timer.c:183
 call_timer_fn+0x192/0x640 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2373 [inline]
 __run_timer_base+0x652/0x8b0 kernel/time/timer.c:2385
 run_timer_base kernel/time/timer.c:2394 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404
 handle_softirqs+0x22a/0x870 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

The buggy address belongs to the object at ffff88806adc8c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of
 freed 512-byte region [ffff88806adc8c00, ffff88806adc8e00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6adc8
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813fea8c80 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fea8c80 dead000000000100 dead000000000122
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0001ab7201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1158, tgid 1158 (kworker/u8:10), ts 87672791802, free_ts 77510569787
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3255 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3444
 new_slab mm/slub.c:3502 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7134
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x2b9/0x620 mm/slub.c:4578
 alloc_from_pcs mm/slub.c:4681 [inline]
 slab_alloc_node mm/slub.c:4815 [inline]
 __do_kmalloc_node mm/slub.c:5218 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5231
 kmalloc_noprof include/linux/slab.h:966 [inline]
 kzalloc_noprof include/linux/slab.h:1200 [inline]
 fib6_info_alloc+0x30/0xf0 net/ipv6/ip6_fib.c:155
 ip6_route_info_create+0x142/0x860 net/ipv6/route.c:3819
 ip6_route_add+0x49/0x1b0 net/ipv6/route.c:3948
 addrconf_add_mroute+0x2d1/0x370 net/ipv6/addrconf.c:2551
 addrconf_add_dev net/ipv6/addrconf.c:2569 [inline]
 addrconf_dev_config net/ipv6/addrconf.c:3483 [inline]
 addrconf_init_auto_addrs+0x4d7/0xa50 net/ipv6/addrconf.c:3571
 addrconf_notify+0xb1e/0x1050 net/ipv6/addrconf.c:3744
 notifier_call_chain+0x1be/0x400 kernel/notifier.c:85
 netif_state_change+0x27d/0x3a0 net/core/dev.c:1603
 __linkwatch_run_queue+0x572/0x840 net/core/link_watch.c:240
page last free pid 5804 tgid 5804 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xed5/0x16d0 mm/page_alloc.c:3040
 folios_put_refs+0x789/0x8d0 mm/swap.c:1002
 free_pages_and_swap_cache+0x2e7/0x5b0 mm/swap_state.c:423
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:138 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:151 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:398 [inline]
 tlb_flush_mmu+0x6d3/0xa30 mm/mmu_gather.c:405
 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:530
 unmap_region+0x2a5/0x330 mm/vma.c:488
 vms_clear_ptes mm/vma.c:1284 [inline]
 vms_complete_munmap_vmas+0x493/0xc60 mm/vma.c:1326
 do_vmi_align_munmap+0x3b7/0x4b0 mm/vma.c:1585
 do_vmi_munmap+0x252/0x2d0 mm/vma.c:1633
 __vm_munmap+0x22c/0x3d0 mm/vma.c:3254
 __do_sys_munmap mm/mmap.c:1078 [inline]
 __se_sys_munmap mm/mmap.c:1075 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:1075
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88806adc8b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88806adc8b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88806adc8c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88806adc8c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806adc8d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	48 85 db             	test   %rbx,%rbx
   5:	0f 85 e8 01 00 00    	jne    0x1f3
   b:	e9 56 05 00 00       	jmp    0x566
  10:	4c 8b 75 d0          	mov    -0x30(%rbp),%r14
  14:	49 83 c4 48          	add    $0x48,%r12
  18:	4c 89 e7             	mov    %r12,%rdi
  1b:	e8 55 ce 1a 0a       	call   0xa1ace75
  20:	e8 50 7e 38 00       	call   0x387e75
  25:	fb                   	sti
  26:	4c 8b 65 c0          	mov    -0x40(%rbp),%r12
* 2a:	49 8d bc 24 30 16 00 	lea    0x1630(%r12),%rdi <-- trapping instruction
  31:	00
  32:	48 89 f8             	mov    %rdi,%rax
  35:	48 c1 e8 03          	shr    $0x3,%rax
  39:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax
  3e:	84 c0                	test   %al,%al

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/24 06:11 upstream 7dff99b35460 41d2fa6a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in rose_t0timer_expiry
2026/02/17 18:03 net-next 37a93dd5c49b 39751c21 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce KASAN: slab-use-after-free Read in rose_t0timer_expiry
2026/02/12 18:37 net-next 37a93dd5c49b 504cb1bf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce KASAN: slab-use-after-free Read in rose_t0timer_expiry
2026/02/11 01:38 net-next ad1f18e985cb 441e25b7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce KASAN: slab-use-after-free Read in rose_t0timer_expiry
2026/02/06 13:11 net-next 24cf78c73831 97745f52 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce KASAN: slab-use-after-free Read in rose_t0timer_expiry
2026/02/06 13:17 net-next 24cf78c73831 97745f52 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce KASAN: slab-use-after-free Write in rose_t0timer_expiry
* Struck through repros no longer work on HEAD.