================================================================== BUG: KASAN: use-after-free in ax25_fillin_cb_from_dev net/ax25/af_ax25.c:468 [inline] BUG: KASAN: use-after-free in ax25_fillin_cb+0x459/0x640 net/ax25/af_ax25.c:495 Read of size 4 at addr ffff88802bfdd138 by task syz.1.167/5301 CPU: 0 PID: 5301 Comm: syz.1.167 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 print_address_description+0x60/0x2d0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:434 [inline] kasan_report+0xdf/0x130 mm/kasan/report.c:451 ax25_fillin_cb_from_dev net/ax25/af_ax25.c:468 [inline] ax25_fillin_cb+0x459/0x640 net/ax25/af_ax25.c:495 ax25_setsockopt+0x8c9/0xa60 net/ax25/af_ax25.c:690 __sys_setsockopt+0x2bf/0x3d0 net/socket.c:2212 __do_sys_setsockopt net/socket.c:2223 [inline] __se_sys_setsockopt net/socket.c:2220 [inline] __x64_sys_setsockopt+0xb1/0xc0 net/socket.c:2220 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f37fcde0799 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:00007f37fb03a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f37fd059fa0 RCX: 00007f37fcde0799 RDX: 0000000000000019 RSI: 0000000000000101 RDI: 0000000000000004 RBP: 00007f37fce76bd9 R08: 0000000000000010 R09: 0000000000000000 R10: 0000200000000240 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f37fd05a038 R14: 00007f37fd059fa0 R15: 00007ffded8480f8 Allocated by task 4980: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522 kmalloc include/linux/slab.h:607 [inline] kzalloc include/linux/slab.h:738 [inline] ax25_dev_device_up+0x50/0x580 net/ax25/ax25_dev.c:55 ax25_device_event+0x483/0x4f0 net/ax25/af_ax25.c:139 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391 call_netdevice_notifiers_extack net/core/dev.c:2074 [inline] call_netdevice_notifiers net/core/dev.c:2088 [inline] __dev_notify_flags+0x194/0x300 net/core/dev.c:8904 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8942 dev_ifsioc+0x130/0xd50 net/core/dev_ioctl.c:324 dev_ioctl+0x545/0xe30 net/core/dev_ioctl.c:572 sock_do_ioctl+0x245/0x320 net/socket.c:1161 sock_ioctl+0x4d2/0x710 net/socket.c:1266 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Freed by task 5200: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:46 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1710 [inline] slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736 slab_free mm/slub.c:3504 [inline] kfree+0xef/0x2a0 mm/slub.c:4564 ax25_dev_put include/net/ax25.h:302 [inline] ax25_release+0x661/0x870 net/ax25/af_ax25.c:1062 __sock_release net/socket.c:651 [inline] sock_close+0xd5/0x240 net/socket.c:1345 __fput+0x234/0x930 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Last potentially related work creation: kasan_save_stack+0x35/0x60 mm/kasan/common.c:38 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348 insert_work+0x54/0x3d0 kernel/workqueue.c:1366 __queue_work+0x9c5/0xd50 kernel/workqueue.c:1532 queue_work_on+0x124/0x1f0 kernel/workqueue.c:1559 queue_work include/linux/workqueue.h:512 [inline] loop_queue_work drivers/block/loop.c:1068 [inline] loop_queue_rq+0x9d8/0xac0 drivers/block/loop.c:2202 __blk_mq_issue_directly block/blk-mq.c:2015 [inline] __blk_mq_try_issue_directly+0x497/0x820 block/blk-mq.c:2071 blk_mq_try_issue_directly+0xaf/0x270 block/blk-mq.c:2102 blk_mq_submit_bio+0xfa1/0x1820 block/blk-mq.c:-1 __submit_bio+0x7d1/0x820 block/blk-core.c:917 __submit_bio_noacct_mq block/blk-core.c:997 [inline] submit_bio_noacct+0x6b0/0x800 block/blk-core.c:1027 submit_bio+0x2c1/0x560 block/blk-core.c:1089 submit_bh+0x23/0x30 fs/buffer.c:3062 ext4_sb_breadahead_unmovable+0xc2/0xe0 fs/ext4/super.c:243 ext4_fill_super+0x4fd0/0x95a0 fs/ext4/super.c:4596 mount_bdev+0x287/0x3c0 fs/super.c:1400 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611 vfs_get_tree+0x88/0x270 fs/super.c:1530 do_new_mount+0x24a/0xa40 fs/namespace.c:3034 do_mount fs/namespace.c:3377 [inline] __do_sys_mount fs/namespace.c:3585 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Second to last potentially related work creation: kasan_save_stack+0x35/0x60 mm/kasan/common.c:38 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348 insert_work+0x54/0x3d0 kernel/workqueue.c:1366 __queue_work+0x9c5/0xd50 kernel/workqueue.c:1532 queue_work_on+0x124/0x1f0 kernel/workqueue.c:1559 queue_work include/linux/workqueue.h:512 [inline] loop_queue_work drivers/block/loop.c:1068 [inline] loop_queue_rq+0x9d8/0xac0 drivers/block/loop.c:2202 __blk_mq_issue_directly block/blk-mq.c:2015 [inline] __blk_mq_try_issue_directly+0x497/0x820 block/blk-mq.c:2071 blk_mq_try_issue_directly+0xaf/0x270 block/blk-mq.c:2102 blk_mq_submit_bio+0xfa1/0x1820 block/blk-mq.c:-1 __submit_bio+0x7d1/0x820 block/blk-core.c:917 __submit_bio_noacct_mq block/blk-core.c:997 [inline] submit_bio_noacct+0x6b0/0x800 block/blk-core.c:1027 submit_bio+0x2c1/0x560 block/blk-core.c:1089 submit_bh+0x23/0x30 fs/buffer.c:3062 __ext4_read_bh fs/ext4/super.c:156 [inline] ext4_read_bh+0x180/0x240 fs/ext4/super.c:180 ext4_read_bh_lock fs/ext4/super.c:195 [inline] __ext4_sb_bread_gfp+0x1d1/0x220 fs/ext4/super.c:217 ext4_sb_bread_unmovable fs/ext4/super.c:234 [inline] ext4_fill_super+0x6f2/0x95a0 fs/ext4/super.c:4001 mount_bdev+0x287/0x3c0 fs/super.c:1400 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611 vfs_get_tree+0x88/0x270 fs/super.c:1530 do_new_mount+0x24a/0xa40 fs/namespace.c:3034 do_mount fs/namespace.c:3377 [inline] __do_sys_mount fs/namespace.c:3585 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 The buggy address belongs to the object at ffff88802bfdd100 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 56 bytes inside of 192-byte region [ffff88802bfdd100, ffff88802bfdd1c0) The buggy address belongs to the page: page:ffffea0000aff740 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2bfdd flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffffea00017cd040 0000000600000004 ffff888016c41a00 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 4719, ts 89874401884, free_ts 89863479807 prep_new_page mm/page_alloc.c:2426 [inline] get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5487 __alloc_pages_node include/linux/gfp.h:570 [inline] alloc_slab_page mm/slub.c:1782 [inline] allocate_slab mm/slub.c:1917 [inline] new_slab+0xb6/0x4b0 mm/slub.c:1980 ___slab_alloc+0x80a/0xdd0 mm/slub.c:3013 __slab_alloc mm/slub.c:3100 [inline] slab_alloc_node mm/slub.c:3191 [inline] __kmalloc_node+0x200/0x3b0 mm/slub.c:4456 kmalloc_array_node include/linux/slab.h:700 [inline] kcalloc_node include/linux/slab.h:705 [inline] memcg_alloc_page_obj_cgroups+0x81/0x120 mm/memcontrol.c:2839 memcg_slab_post_alloc_hook mm/slab.h:313 [inline] slab_post_alloc_hook+0xba/0x380 mm/slab.h:526 slab_alloc_node mm/slub.c:3225 [inline] slab_alloc mm/slub.c:3233 [inline] kmem_cache_alloc+0x100/0x290 mm/slub.c:3238 __d_alloc+0x2a/0x6f0 fs/dcache.c:1749 d_alloc+0x4a/0x250 fs/dcache.c:1828 lookup_one_qstr_excl+0xc6/0x240 fs/namei.c:1567 filename_create+0x23a/0x470 fs/namei.c:3844 do_mkdirat+0xa5/0x5b0 fs/namei.c:4088 __do_sys_mkdirat fs/namei.c:4113 [inline] __se_sys_mkdirat fs/namei.c:4111 [inline] __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1340 [inline] free_pcp_prepare mm/page_alloc.c:1391 [inline] free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317 free_unref_page_list+0x119/0x820 mm/page_alloc.c:3433 release_pages+0x186c/0x1be0 mm/swap.c:963 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline] tlb_flush_mmu_free mm/mmu_gather.c:240 [inline] tlb_flush_mmu mm/mmu_gather.c:247 [inline] tlb_finish_mmu+0x176/0x300 mm/mmu_gather.c:338 exit_mmap+0x3d0/0x640 mm/mmap.c:3218 __mmput+0x115/0x3b0 kernel/fork.c:1127 exec_mmap+0x51d/0x610 fs/exec.c:1035 begin_new_exec+0x7e8/0x1160 fs/exec.c:1293 load_elf_binary+0x99c/0x28e0 fs/binfmt_elf.c:1001 search_binary_handler fs/exec.c:1742 [inline] exec_binprm fs/exec.c:1783 [inline] bprm_execve+0xaee/0x1840 fs/exec.c:1852 do_execveat_common+0x51e/0x6d0 fs/exec.c:1957 do_execve fs/exec.c:2027 [inline] __do_sys_execve fs/exec.c:2103 [inline] __se_sys_execve fs/exec.c:2098 [inline] __x64_sys_execve+0x8e/0xa0 fs/exec.c:2098 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Memory state around the buggy address: ffff88802bfdd000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88802bfdd080: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc >ffff88802bfdd100: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88802bfdd180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88802bfdd200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================