================================================================== 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+0x39c/0x588 net/ax25/af_ax25.c:495 Read of size 4 at addr ffff0000c0878238 by task syz-executor178/4022 CPU: 1 PID: 4022 Comm: syz-executor178 Not tainted 5.15.178-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_load4_noabort+0x44/0x50 mm/kasan/report_generic.c:308 ax25_fillin_cb_from_dev net/ax25/af_ax25.c:468 [inline] ax25_fillin_cb+0x39c/0x588 net/ax25/af_ax25.c:495 ax25_setsockopt+0x980/0xcdc net/ax25/af_ax25.c:690 __sys_setsockopt+0x3a8/0x6b4 net/socket.c:2203 __do_sys_setsockopt net/socket.c:2214 [inline] __se_sys_setsockopt net/socket.c:2211 [inline] __arm64_sys_setsockopt+0xb8/0xd4 net/socket.c:2211 __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 Allocated by task 4020: 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+0x500/0x58c 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+0x2ac/0x534 dev_change_flags+0xc8/0x154 net/core/dev.c:8897 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+0x4f0/0x8ac 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 4021: 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:280 ____fput+0x20/0x30 fs/file_table.c:308 task_work_run+0x130/0x1e4 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x670/0x20bc kernel/exit.c:874 do_group_exit+0x110/0x268 kernel/exit.c:996 __do_sys_exit_group kernel/exit.c:1007 [inline] __se_sys_exit_group kernel/exit.c:1005 [inline] __wake_up_parent+0x0/0x60 kernel/exit.c:1005 __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 ffff0000c0878200 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 56 bytes inside of 256-byte region [ffff0000c0878200, ffff0000c0878300) The buggy address belongs to the page: page:00000000f4a9213a refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x100878 head:00000000f4a9213a order:1 compound_mapcount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 0000000000000000 0000000800000001 ffff0000c0002480 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000c0878100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000c0878180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000c0878200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000c0878280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000c0878300: 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 be8002560000155d Mem abort info: ESR = 0x0000000096000021 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x21: alignment fault Data abort info: ISV = 0, ISS = 0x00000021 CM = 0, WnR = 0 [be8002560000155d] address between user and kernel address ranges Internal error: Oops: 0000000096000021 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 4022 Comm: syz-executor178 Tainted: G B 5.15.178-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 : __lse_atomic_fetch_sub_release arch/arm64/include/asm/atomic_lse.h:161 [inline] pc : arch_atomic_fetch_sub_release arch/arm64/include/asm/atomic.h:51 [inline] pc : atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:168 [inline] pc : __refcount_dec include/linux/refcount.h:338 [inline] pc : refcount_dec include/linux/refcount.h:359 [inline] pc : dev_put include/linux/netdevice.h:4189 [inline] pc : ax25_release+0x50c/0x82c net/ax25/af_ax25.c:1061 lr : arch_atomic_fetch_sub_release arch/arm64/include/asm/atomic.h:51 [inline] lr : atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:168 [inline] lr : __refcount_dec include/linux/refcount.h:338 [inline] lr : refcount_dec include/linux/refcount.h:359 [inline] lr : dev_put include/linux/netdevice.h:4189 [inline] lr : ax25_release+0x504/0x82c net/ax25/af_ax25.c:1061 sp : ffff80001d6979f0 x29: ffff80001d697a10 x28: dfff800000000000 x27: ffff0000d8991080 x26: ffff0000c1186028 x25: 0000000000000002 x24: 00000000ffffffff x23: be8002560000155d x22: ffff0000c0878200 x21: ffff0000dbe95418 x20: ffff0000d8991000 x19: 1fffe00018230c05 x18: 0000000000000000 x17: 0000000000000000 x16: ffff8000084c44a8 x15: 0000000000000002 x14: 0000000011b4a01c x13: 00000000373d76dd x12: 0000000000000001 x11: 0000000000000000 x10: 0000000000000000 x9 : ffff0000cb450000 x8 : ffff800010dd0198 x7 : 0000000000000000 x6 : ffff8000083b965c x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800010dd018c x2 : 0000000000000001 x1 : 0000000000000004 x0 : 0000000000000001 Call trace: __lse_atomic_fetch_sub_release arch/arm64/include/asm/atomic_lse.h:161 [inline] arch_atomic_fetch_sub_release arch/arm64/include/asm/atomic.h:51 [inline] atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:168 [inline] __refcount_dec include/linux/refcount.h:338 [inline] refcount_dec include/linux/refcount.h:359 [inline] dev_put include/linux/netdevice.h:4189 [inline] ax25_release+0x50c/0x82c net/ax25/af_ax25.c:1061 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x1fc net/socket.c:1336 __fput+0x1c4/0x800 fs/file_table.c:280 ____fput+0x20/0x30 fs/file_table.c:308 task_work_run+0x130/0x1e4 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x670/0x20bc kernel/exit.c:874 do_group_exit+0x110/0x268 kernel/exit.c:996 __do_sys_exit_group kernel/exit.c:1007 [inline] __se_sys_exit_group kernel/exit.c:1005 [inline] __wake_up_parent+0x0/0x60 kernel/exit.c:1005 __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 Code: d503201f 97c51913 52800038 4b1803f8 (b87802f8) ---[ end trace 45b11c72e3a43bcc ]--- ---------------- Code disassembly (best guess): 0: d503201f nop 4: 97c51913 bl 0xffffffffff146450 8: 52800038 mov w24, #0x1 // #1 c: 4b1803f8 neg w24, w24 * 10: b87802f8 ldaddl w24, w24, [x23] <-- trapping instruction