==================================================================
BUG: KASAN: use-after-free in rose_send_frame+0x73/0x220 net/rose/rose_link.c:101
Read of size 8 at addr ffff88801ebd6820 by task syz.4.804/7714

CPU: 0 PID: 7714 Comm: syz.4.804 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 rose_send_frame+0x73/0x220 net/rose/rose_link.c:101
 rose_transmit_restart_request net/rose/rose_link.c:198 [inline]
 rose_t0timer_expiry+0x13f/0x350 net/rose/rose_link.c:83
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:get_current kernel/rcu/tree_plugin.h:401 [inline]
RIP: 0010:rcu_preempt_read_enter kernel/rcu/tree_plugin.h:379 [inline]
RIP: 0010:__rcu_read_lock+0x0/0x50 kernel/rcu/tree_plugin.h:402
Code: fb ff ff 44 89 f1 80 e1 07 38 c1 0f 8c 0f fb ff ff 4c 89 f7 e8 71 20 66 00 e9 02 fb ff ff 66 2e 0f 1f 84 00 00 00 00 00 66 90 <53> 65 48 8b 1d 17 32 95 7e 48 81 c3 3c 04 00 00 48 89 d8 48 c1 e8
RSP: 0018:ffffc9000e0873e0 EFLAGS: 00000293
RAX: ffffffff81dd8d12 RBX: 0000000000000001 RCX: ffff88801f660000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffea000171c400
RBP: 0000000000000001 R08: ffffffff8e1fc32f R09: 1ffffffff1c3f865
R10: dffffc0000000000 R11: fffffbfff1c3f866 R12: 00007f9e08360000
R13: ffffea000171c400 R14: ffffea000171c400 R15: ffffea000171c400
 rcu_read_lock include/linux/rcupdate.h:789 [inline]
 page_ext_get+0x17/0x2a0 mm/page_ext.c:157
 page_table_check_clear+0x4a/0x6b0 mm/page_table_check.c:71
 ptep_get_and_clear_full arch/x86/include/asm/jump_label.h:-1 [inline]
 zap_pte_range mm/memory.c:1433 [inline]
 zap_pmd_range mm/memory.c:1572 [inline]
 zap_pud_range mm/memory.c:1601 [inline]
 zap_p4d_range mm/memory.c:1622 [inline]
 unmap_page_range+0x192d/0x2500 mm/memory.c:1643
 unmap_vmas+0x260/0x390 mm/memory.c:1728
 exit_mmap+0x20d/0x960 mm/mmap.c:3250
 __mmput+0x118/0x3c0 kernel/fork.c:1205
 exit_mm+0x1fe/0x2d0 kernel/exit.c:565
 do_exit+0x905/0x2480 kernel/exit.c:867
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 get_signal+0x1272/0x1350 kernel/signal.c:2871
 arch_do_signal_or_restart+0xc4/0x1350 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9e0959acb9
Code: Unable to access opcode bytes at 0x7f9e0959ac8f.
RSP: 002b:00007f9e077f60e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f9e09815fa8 RCX: 00007f9e0959acb9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f9e09815fa8
RBP: 00007f9e09815fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9e09816038 R14: 00007ffd6bb89000 R15: 00007ffd6bb890e8
 </TASK>

Allocated by task 4421:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kmalloc include/linux/slab.h:563 [inline]
 rose_add_node+0x227/0xea0 net/rose/rose_route.c:85
 rose_rt_ioctl+0xb63/0xf70 net/rose/rose_route.c:748
 rose_ioctl+0x2a7/0x7d0 net/rose/af_rose.c:1381
 sock_do_ioctl+0xfb/0x320 net/socket.c:1201
 sock_ioctl+0x4d2/0x710 net/socket.c:1320
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 7715:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3700
 rose_neigh_put include/net/rose.h:166 [inline]
 rose_timer_expiry+0x4a7/0x5d0 net/rose/rose_timer.c:183
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691

The buggy address belongs to the object at ffff88801ebd6800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 32 bytes inside of
 512-byte region [ffff88801ebd6800, ffff88801ebd6a00)

The buggy address belongs to the physical page:
page:ffffea00007af500 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88801ebd7800 pfn:0x1ebd4
head:ffffea00007af500 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea0000c2e708 ffffea0000b34508 ffff888017441c80
raw: ffff88801ebd7800 000000000010000c 00000001ffffffff 0000000000000000
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 1, tgid 1 (swapper/0), ts 6058515058, free_ts 0
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a1e/0x1ab0 mm/page_alloc.c:4328
 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5614
 alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2115
 alloc_slab_page+0x5d/0x160 mm/slub.c:1799
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x87/0x2c0 mm/slub.c:1997
 ___slab_alloc+0xbc6/0x1240 mm/slub.c:3154
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398
 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1026
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 device_private_init drivers/base/core.c:3541 [inline]
 device_add+0xba/0xfb0 drivers/base/core.c:3591
 tty_register_device_attr+0x431/0x980 drivers/tty/tty_io.c:3250
 tty_register_device drivers/tty/tty_io.c:3185 [inline]
 tty_register_driver+0x59c/0xb20 drivers/tty/tty_io.c:3449
 legacy_pty_init+0x3a6/0x5fd drivers/tty/pty.c:579
 pty_init+0xa/0x12 drivers/tty/pty.c:943
 do_one_initcall+0x26a/0x840 init/main.c:1310
 do_initcall_level+0x137/0x1e4 init/main.c:1383
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88801ebd6700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801ebd6780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801ebd6800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff88801ebd6880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801ebd6900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	ff 44 89 f1          	incl   -0xf(%rcx,%rcx,4)
   4:	80 e1 07             	and    $0x7,%cl
   7:	38 c1                	cmp    %al,%cl
   9:	0f 8c 0f fb ff ff    	jl     0xfffffb1e
   f:	4c 89 f7             	mov    %r14,%rdi
  12:	e8 71 20 66 00       	call   0x662088
  17:	e9 02 fb ff ff       	jmp    0xfffffb1e
  1c:	66 2e 0f 1f 84 00 00 	cs nopw 0x0(%rax,%rax,1)
  23:	00 00 00
  26:	66 90                	xchg   %ax,%ax
* 28:	53                   	push   %rbx <-- trapping instruction
  29:	65 48 8b 1d 17 32 95 	mov    %gs:0x7e953217(%rip),%rbx        # 0x7e953248
  30:	7e
  31:	48 81 c3 3c 04 00 00 	add    $0x43c,%rbx
  38:	48 89 d8             	mov    %rbx,%rax
  3b:	48                   	rex.W
  3c:	c1                   	.byte 0xc1
  3d:	e8                   	.byte 0xe8