syzbot


KASAN: use-after-free Read in ax25_addr_ax25dev

Status: upstream: reported on 2025/01/31 08:06
Reported-by: syzbot+1de283b57bc195a3107b@syzkaller.appspotmail.com
First crash: 43d, last: 21d

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in ax25_addr_ax25dev+0x5c/0x19c net/ax25/ax25_dev.c:38
Read of size 8 at addr ffff0000c8699408 by task syz.8.1458/9204

CPU: 0 PID: 9204 Comm: syz.8.1458 Not tainted 5.15.178-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
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_addr_ax25dev+0x5c/0x19c net/ax25/ax25_dev.c:38
 ax25_ctl_ioctl net/ax25/af_ax25.c:378 [inline]
 ax25_ioctl+0x112c/0x1fb4 net/ax25/af_ax25.c:1827
 sock_do_ioctl+0x134/0x2dc net/socket.c:1140
 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

Allocated by task 5854:
 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 9164:
 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
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 do_notify_resume+0x262c/0x32b8 arch/arm64/kernel/signal.c:946
 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
 __call_rcu kernel/rcu/tree.c:3007 [inline]
 call_rcu+0x118/0xb40 kernel/rcu/tree.c:3087
 neigh_parms_release+0x1b0/0x228 net/core/neighbour.c:1674
 addrconf_ifdown+0x1510/0x1814 net/ipv6/addrconf.c:3932
 addrconf_notify+0x350/0xc58
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:391
 call_netdevice_notifiers_info net/core/dev.c:2018 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2030 [inline]
 call_netdevice_notifiers net/core/dev.c:2044 [inline]
 unregister_netdevice_many+0xec4/0x189c net/core/dev.c:11102
 default_device_exit_batch+0x4c0/0x520 net/core/dev.c:11635
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x6bc/0xa9c net/core/net_namespace.c:618
 process_one_work+0x790/0x11b8 kernel/workqueue.c:2310
 worker_thread+0x910/0x1034 kernel/workqueue.c:2457
 kthread+0x37c/0x45c kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

Second to 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
 kobject_uevent_env+0x678/0x898 lib/kobject_uevent.c:633
 kobject_uevent+0x2c/0x3c lib/kobject_uevent.c:657
 tty_register_device_attr+0x48c/0x7cc drivers/tty/tty_io.c:3311
 tty_register_device drivers/tty/tty_io.c:3224 [inline]
 tty_register_driver+0x4d0/0xa18 drivers/tty/tty_io.c:3482
 legacy_pty_init+0x318/0x554 drivers/tty/pty.c:579
 pty_init+0x14/0x28 drivers/tty/pty.c:943
 do_one_initcall+0x234/0x990 init/main.c:1302
 do_initcall_level+0x154/0x214 init/main.c:1375
 do_initcalls+0x58/0xac init/main.c:1391
 do_basic_setup+0x8c/0xa0 init/main.c:1410
 kernel_init_freeable+0x460/0x640 init/main.c:1615
 kernel_init+0x24/0x294 init/main.c:1506
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

The buggy address belongs to the object at ffff0000c8699400
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 8 bytes inside of
 256-byte region [ffff0000c8699400, ffff0000c8699500)
The buggy address belongs to the page:
page:000000005de3de07 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x108698
head:000000005de3de07 order:1 compound_mapcount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 fffffc0003050300 0000000200000002 ffff0000c0002480
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000c8699300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000c8699380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000c8699400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff0000c8699480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000c8699500: 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 f78380a6400004ea
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
[f78380a6400004ea] address between user and kernel address ranges
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 9204 Comm: syz.8.1458 Tainted: G    B             5.15.178-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : ax25_addr_ax25dev+0x68/0x19c net/ax25/ax25_dev.c:38
lr : ax25_addr_ax25dev+0x5c/0x19c net/ax25/ax25_dev.c:38
sp : ffff8000216177c0
x29: ffff8000216177c0 x28: ffff7000042c2f04 x27: 1ffff000042c2f0c
x26: 1ffff000042c2f0d x25: 0000000000000047 x24: ffff800021617868
x23: dfff800000000000 x22: bc20053200002754 x21: 0000000000000000
x20: ffff0000c8699400 x19: ffff800021617840 x18: 0000000000000203
x17: 0000000000000002 x16: ffff80000824ec08 x15: 00000000ffffffff
x14: ffff0000d8030000 x13: 0000000000000001 x12: 0000000000080000
x11: 000000000002d593 x10: ffff80002c439000 x9 : 0000000000000000
x8 : 178400a6400004ea x7 : 0000000000000000 x6 : 0000000000000001
x5 : ffff800021616e58 x4 : 0000000000000000 x3 : ffff80000819c3f0
x2 : 0000000000000001 x1 : 0000000000000001 x0 : 0000000000000001
Call trace:
 ax25_addr_ax25dev+0x68/0x19c net/ax25/ax25_dev.c:38
 ax25_ctl_ioctl net/ax25/af_ax25.c:378 [inline]
 ax25_ioctl+0x112c/0x1fb4 net/ax25/af_ax25.c:1827
 sock_do_ioctl+0x134/0x2dc net/socket.c:1140
 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
Code: 97c55d03 f94002c8 910e2116 d343fec8 (38776908) 
---[ end trace 70ff0a822fc84b4c ]---
----------------
Code disassembly (best guess):
   0:	97c55d03 	bl	0xffffffffff15740c
   4:	f94002c8 	ldr	x8, [x22]
   8:	910e2116 	add	x22, x8, #0x388
   c:	d343fec8 	lsr	x8, x22, #3
* 10:	38776908 	ldrb	w8, [x8, x23] <-- trapping instruction

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/22 03:25 linux-5.15.y c16c81c81336 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in ax25_addr_ax25dev
2025/01/31 08:06 linux-5.15.y 003148680b79 4c6ac32f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in ax25_addr_ax25dev
2025/01/31 08:06 linux-5.15.y 003148680b79 4c6ac32f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 KASAN: use-after-free Read in ax25_addr_ax25dev
2025/01/31 08:40 linux-5.15.y 003148680b79 4c6ac32f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 BUG: unable to handle kernel paging request in ax25_addr_ax25dev
* Struck through repros no longer work on HEAD.