================================================================== BUG: KASAN: use-after-free in ax25_send_control+0x70/0x430 net/ax25/ax25_subr.c:152 Read of size 8 at addr ffff0000c1837608 by task syz.3.772/7036 CPU: 0 PID: 7036 Comm: syz.3.772 Not tainted 5.15.179-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call trace: dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 print_address_description+0x7c/0x3f0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:434 [inline] kasan_report+0x174/0x1e4 mm/kasan/report.c:451 __asan_report_load8_noabort+0x44/0x50 mm/kasan/report_generic.c:309 ax25_send_control+0x70/0x430 net/ax25/ax25_subr.c:152 ax25_release+0x32c/0x82c net/ax25/af_ax25.c:1006 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x1fc net/socket.c:1336 __fput+0x1c4/0x800 fs/file_table.c:311 ____fput+0x20/0x30 fs/file_table.c:339 task_work_run+0x130/0x1e4 kernel/task_work.c:188 get_signal+0x1450/0x1550 kernel/signal.c:2672 do_signal arch/arm64/kernel/signal.c:890 [inline] do_notify_resume+0x3d0/0x32b8 arch/arm64/kernel/signal.c:943 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xfc/0x1f0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Allocated by task 4178: 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+0xbc/0xfc mm/kasan/common.c:513 __kasan_kmalloc+0x10/0x1c mm/kasan/common.c:522 kasan_kmalloc include/linux/kasan.h:264 [inline] kmem_cache_alloc_trace+0x27c/0x47c mm/slub.c:3247 kmalloc include/linux/slab.h:591 [inline] kzalloc include/linux/slab.h:721 [inline] ax25_dev_device_up+0x5c/0x548 net/ax25/ax25_dev.c:55 ax25_device_event+0x504/0x590 net/ax25/af_ax25.c:139 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:391 __dev_notify_flags+0x2b4/0x540 dev_change_flags+0xc8/0x154 net/core/dev.c:8928 dev_ifsioc+0x140/0xfe4 net/core/dev_ioctl.c:324 dev_ioctl+0x4e0/0xd3c net/core/dev_ioctl.c:587 sock_do_ioctl+0x1dc/0x2dc net/socket.c:1154 sock_ioctl+0x4f4/0x8b0 net/socket.c:1257 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Freed by task 7019: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4c/0x84 mm/kasan/common.c:46 kasan_set_free_info+0x28/0x4c mm/kasan/generic.c:360 ____kasan_slab_free+0x118/0x164 mm/kasan/common.c:366 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1705 [inline] slab_free_freelist_hook+0x128/0x1ec mm/slub.c:1731 slab_free mm/slub.c:3499 [inline] kfree+0x178/0x410 mm/slub.c:4559 ax25_dev_put include/net/ax25.h:302 [inline] ax25_release+0x57c/0x82c net/ax25/af_ax25.c:1062 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x1fc net/socket.c:1336 __fput+0x1c4/0x800 fs/file_table.c:311 ____fput+0x20/0x30 fs/file_table.c:339 task_work_run+0x130/0x1e4 kernel/task_work.c:188 get_signal+0x1450/0x1550 kernel/signal.c:2672 do_signal arch/arm64/kernel/signal.c:890 [inline] do_notify_resume+0x3d0/0x32b8 arch/arm64/kernel/signal.c:943 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xfc/0x1f0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Last potentially related work creation: kasan_save_stack+0x38/0x68 mm/kasan/common.c:38 kasan_record_aux_stack+0xd4/0x11c mm/kasan/generic.c:348 insert_work+0x64/0x394 kernel/workqueue.c:1366 __queue_work+0xb84/0x114c kernel/workqueue.c:1532 queue_work_on+0xc4/0x17c kernel/workqueue.c:1559 queue_work include/linux/workqueue.h:512 [inline] call_usermodehelper_exec+0x238/0x484 kernel/umh.c:435 call_modprobe kernel/kmod.c:98 [inline] __request_module+0x4c0/0xb34 kernel/kmod.c:170 dev_load+0x1d8/0x1ec net/core/dev_ioctl.c:448 dev_ioctl+0x3a4/0xd3c net/core/dev_ioctl.c:511 sock_do_ioctl+0x1dc/0x2dc net/socket.c:1154 sock_ioctl+0x4f4/0x8b0 net/socket.c:1257 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 The buggy address belongs to the object at ffff0000c1837600 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 8 bytes inside of 256-byte region [ffff0000c1837600, ffff0000c1837700) The buggy address belongs to the page: page:0000000081eb41a6 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101836 head:0000000081eb41a6 order:1 compound_mapcount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 fffffc0003050a00 0000000900000009 ffff0000c0002480 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000c1837500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000c1837580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000c1837600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000c1837680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000c1837700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Unable to handle kernel paging request at virtual address f0ff8081c0000388 Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004 CM = 0, WnR = 0 [f0ff8081c0000388] address between user and kernel address ranges Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 7036 Comm: syz.3.772 Tainted: G B 5.15.179-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : ax25_send_control+0x84/0x430 net/ax25/ax25_subr.c:152 lr : ax25_send_control+0x70/0x430 net/ax25/ax25_subr.c:152 sp : ffff800020b877e0 x29: ffff800020b877e0 x28: dfff800000000000 x27: ffff0000ce0ed080 x26: 1fffe0001aaad005 x25: dfff800000000000 x24: ffff0000d5568028 x23: 0000000000000043 x22: 0000000000000001 x21: 8800040e00001c41 x20: ffff0000d5568000 x19: 0000000000000001 x18: 1fffe0003682e78e x17: 1fffe0003682e78e x16: ffff800011b59ca8 x15: ffff800014c0f2a0 x14: ffff0001b4173c80 x13: ffff0001b4173c7c x12: 0000000000080000 x11: 0000000000029b16 x10: ffff8000245a9000 x9 : 0000000000000002 x8 : 11000081c0000388 x7 : 0000000000000000 x6 : ffff80000826b1e8 x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff80000819cb88 x2 : 0000000000000001 x1 : 0000000000000001 x0 : 0000000000000001 Call trace: ax25_send_control+0x84/0x430 net/ax25/ax25_subr.c:152 ax25_release+0x32c/0x82c net/ax25/af_ax25.c:1006 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x1fc net/socket.c:1336 __fput+0x1c4/0x800 fs/file_table.c:311 ____fput+0x20/0x30 fs/file_table.c:339 task_work_run+0x130/0x1e4 kernel/task_work.c:188 get_signal+0x1450/0x1550 kernel/signal.c:2672 do_signal arch/arm64/kernel/signal.c:890 [inline] do_notify_resume+0x3d0/0x32b8 arch/arm64/kernel/signal.c:943 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xfc/0x1f0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 Code: 91035915 d343fea8 12000aa9 11000529 (38f96908) ---[ end trace 1b87fb46178d15d3 ]--- ---------------- Code disassembly (best guess): 0: 91035915 add x21, x8, #0xd6 4: d343fea8 lsr x8, x21, #3 8: 12000aa9 and w9, w21, #0x7 c: 11000529 add w9, w9, #0x1 * 10: 38f96908 ldrsb w8, [x8, x25] <-- trapping instruction