================================================================== 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 ffff88802f81ff32 by task syz.1.574/6637 CPU: 0 UID: 0 PID: 6637 Comm: syz.1.574 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 nr_dec_obs net/netrom/nr_route.c:471 [inline] nr_rt_ioctl+0x594/0xd50 net/netrom/nr_route.c:692 sock_do_ioctl+0xdc/0x300 net/socket.c:1254 sock_ioctl+0x576/0x790 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+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f78ad18f6c9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe114d3e18 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f78ad3e5fa0 RCX: 00007f78ad18f6c9 RDX: 0000000000000000 RSI: 00000000000089e2 RDI: 0000000000000005 RBP: 00007f78ad211f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f78ad3e5fa0 R14: 00007f78ad3e5fa0 R15: 0000000000000002 Allocated by task 6637: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 poison_kmalloc_redzone mm/kasan/common.c:400 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:417 kasan_kmalloc include/linux/kasan.h:262 [inline] __kmalloc_cache_noprof+0x3d5/0x6f0 mm/slub.c:5771 kmalloc_noprof include/linux/slab.h:957 [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+0xdc/0x300 net/socket.c:1254 sock_ioctl+0x576/0x790 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+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6637: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587 kasan_save_free_info mm/kasan/kasan.h:406 [inline] poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2543 [inline] slab_free mm/slub.c:6638 [inline] kfree+0x19a/0x6d0 mm/slub.c:6845 nr_dec_obs net/netrom/nr_route.c:469 [inline] nr_rt_ioctl+0x2e7/0xd50 net/netrom/nr_route.c:692 sock_do_ioctl+0xdc/0x300 net/socket.c:1254 sock_ioctl+0x576/0x790 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+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88802f81ff00 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 50 bytes inside of freed 64-byte region [ffff88802f81ff00, ffff88802f81ff40) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2f81f anon flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000000 ffff88801a0268c0 0000000000000000 dead000000000001 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 18096360358, free_ts 0 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850 prep_new_page mm/page_alloc.c:1858 [inline] get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3884 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:3059 [inline] allocate_slab+0x96/0x350 mm/slub.c:3232 new_slab mm/slub.c:3286 [inline] ___slab_alloc+0xf56/0x1990 mm/slub.c:4655 __slab_alloc+0x65/0x100 mm/slub.c:4778 __slab_alloc_node mm/slub.c:4854 [inline] slab_alloc_node mm/slub.c:5276 [inline] __do_kmalloc_node mm/slub.c:5649 [inline] __kmalloc_noprof+0x471/0x7f0 mm/slub.c:5662 kmalloc_noprof include/linux/slab.h:961 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] kobject_get_path+0xc5/0x2d0 lib/kobject.c:161 kobject_uevent_env+0x292/0x8c0 lib/kobject_uevent.c:545 netdev_queue_add_kobject net/core/net-sysfs.c:2013 [inline] netdev_queue_update_kobjects+0x346/0x6c0 net/core/net-sysfs.c:2056 register_queue_kobjects net/core/net-sysfs.c:2119 [inline] netdev_register_kobject+0x258/0x310 net/core/net-sysfs.c:2362 register_netdevice+0x126c/0x1ae0 net/core/dev.c:11383 register_netdev+0x40/0x60 net/core/dev.c:11499 rose_proto_init+0x146/0x730 net/rose/af_rose.c:1593 do_one_initcall+0x236/0x820 init/main.c:1283 page_owner free stack trace missing Memory state around the buggy address: ffff88802f81fe00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88802f81fe80: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc >ffff88802f81ff00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff88802f81ff80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88802f820000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================