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BUG: KASAN: slab-use-after-free in nr_dec_obs net/netrom/nr_route.c:471 [inline]
BUG: KASAN: slab-use-after-free in nr_rt_ioctl+0x594/0xd50 net/netrom/nr_route.c:692
Read of size 2 at addr ffff888033b54232 by task syz-executor412/7816

CPU: 0 UID: 0 PID: 7816 Comm: syz-executor412 Not tainted 6.15.0-rc3-syzkaller-00141-gb936a9b8d4a5 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xb4/0x290 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 nr_dec_obs net/netrom/nr_route.c:471 [inline]
 nr_rt_ioctl+0x594/0xd50 net/netrom/nr_route.c:692
 sock_do_ioctl+0xd9/0x300 net/socket.c:1190
 sock_ioctl+0x576/0x790 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5905f487e9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 1a 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc8ef8e778 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007f5905f487e9
RDX: 0000000000000000 RSI: 00000000000089e2 RDI: 0000000000000004
RBP: 0000000000000000 R08: 00007f5905f96214 R09: 00007f5905f96214
R10: 00007f5905f96214 R11: 0000000000000246 R12: 00007ffc8ef8e79c
R13: 00007ffc8ef8e7d0 R14: 00007ffc8ef8e7b0 R15: 0000000000000182
 </TASK>

Allocated by task 7815:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4372
 kmalloc_noprof include/linux/slab.h:905 [inline]
 nr_add_node+0x7f8/0x2570 net/netrom/nr_route.c:146
 nr_rt_ioctl+0xc12/0xd50 net/netrom/nr_route.c:651
 sock_do_ioctl+0xd9/0x300 net/socket.c:1190
 sock_ioctl+0x576/0x790 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 7816:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2398 [inline]
 slab_free mm/slub.c:4656 [inline]
 kfree+0x193/0x440 mm/slub.c:4855
 nr_dec_obs net/netrom/nr_route.c:469 [inline]
 nr_rt_ioctl+0x2e7/0xd50 net/netrom/nr_route.c:692
 sock_do_ioctl+0xd9/0x300 net/socket.c:1190
 sock_ioctl+0x576/0x790 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888033b54200
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 50 bytes inside of
 freed 64-byte region [ffff888033b54200, ffff888033b54240)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33b54
anon flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801a0418c0 ffffea0000bc6a80 dead000000000005
raw: 0000000000000000 0000000080200020 00000000f5000000 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 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0), ts 25393010278, free_ts 25391654273
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1d8/0x230 mm/page_alloc.c:1718
 prep_new_page mm/page_alloc.c:1726 [inline]
 get_page_from_freelist+0x21ce/0x22b0 mm/page_alloc.c:3688
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4970
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2301
 alloc_slab_page mm/slub.c:2468 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2632
 new_slab mm/slub.c:2686 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3872
 __slab_alloc mm/slub.c:3962 [inline]
 __slab_alloc_node mm/slub.c:4037 [inline]
 slab_alloc_node mm/slub.c:4198 [inline]
 __kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4367
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 add_sysfs_param+0x610/0xa20 kernel/params.c:641
 kernel_add_sysfs_param+0xb4/0x130 kernel/params.c:814
 param_sysfs_builtin+0x1de/0x290 kernel/params.c:853
 param_sysfs_builtin_init+0x32/0x40 kernel/params.c:987
 do_one_initcall+0x233/0x820 init/main.c:1257
 do_initcall_level+0x137/0x1f0 init/main.c:1319
 do_initcalls+0x69/0xd0 init/main.c:1335
 kernel_init_freeable+0x3d9/0x570 init/main.c:1567
 kernel_init+0x1d/0x1d0 init/main.c:1457
page last free pid 10 tgid 10 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_frozen_pages+0xb0e/0xcd0 mm/page_alloc.c:2725
 vfree+0x1a6/0x330 mm/vmalloc.c:3383
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3303
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xadb/0x17a0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888033b54100: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888033b54180: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888033b54200: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                     ^
 ffff888033b54280: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
 ffff888033b54300: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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