==================================================================
BUG: KASAN: slab-use-after-free in gsm_cleanup_mux+0x720/0x7f4 drivers/tty/n_gsm.c:3052
Read of size 4 at addr ffff00012cf7e00c by task syz-executor.3/9108

CPU: 0 PID: 9108 Comm: syz-executor.3 Not tainted 6.4.0-rc3-syzkaller-geb0f1697d729 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
 show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:351 [inline]
 print_report+0x174/0x514 mm/kasan/report.c:462
 kasan_report+0xd4/0x130 mm/kasan/report.c:572
 __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
 gsm_cleanup_mux+0x720/0x7f4 drivers/tty/n_gsm.c:3052
 gsm_config drivers/tty/n_gsm.c:3327 [inline]
 gsmld_ioctl+0x13bc/0x221c drivers/tty/n_gsm.c:3733
 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2786
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

Allocated by task 9090:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4c/0x7c mm/kasan/common.c:52
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:510
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:196 [inline]
 kmalloc_trace+0x70/0x88 mm/slab_common.c:1062
 kmalloc include/linux/slab.h:559 [inline]
 kzalloc include/linux/slab.h:680 [inline]
 gsm_dlci_alloc+0x64/0x53c drivers/tty/n_gsm.c:2618
 gsm_activate_mux+0x30/0x268 drivers/tty/n_gsm.c:3100
 gsm_config drivers/tty/n_gsm.c:3355 [inline]
 gsmld_ioctl+0x162c/0x221c drivers/tty/n_gsm.c:3733
 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2786
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

Freed by task 9090:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4c/0x7c mm/kasan/common.c:52
 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:521
 ____kasan_slab_free+0x144/0x1c0 mm/kasan/common.c:236
 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:244
 kasan_slab_free include/linux/kasan.h:162 [inline]
 slab_free_hook mm/slub.c:1781 [inline]
 slab_free_freelist_hook mm/slub.c:1807 [inline]
 slab_free mm/slub.c:3786 [inline]
 __kmem_cache_free+0x2a8/0x49c mm/slub.c:3799
 kfree+0xb8/0x19c mm/slab_common.c:1015
 gsm_dlci_free+0x11c/0x168 drivers/tty/n_gsm.c:2671
 tty_port_destructor drivers/tty/tty_port.c:296 [inline]
 kref_put include/linux/kref.h:65 [inline]
 tty_port_put+0xfc/0x190 drivers/tty/tty_port.c:311
 dlci_put drivers/tty/n_gsm.c:2681 [inline]
 gsm_dlci_release drivers/tty/n_gsm.c:2714 [inline]
 gsm_cleanup_mux+0x4ac/0x7f4 drivers/tty/n_gsm.c:3074
 gsm_config drivers/tty/n_gsm.c:3327 [inline]
 gsmld_ioctl+0x13bc/0x221c drivers/tty/n_gsm.c:3733
 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2786
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

Last potentially related work creation:
 kasan_save_stack+0x40/0x6c mm/kasan/common.c:45
 __kasan_record_aux_stack+0xcc/0xe8 mm/kasan/generic.c:491
 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:501
 __call_rcu_common kernel/rcu/tree.c:2627 [inline]
 call_rcu+0x104/0xaf4 kernel/rcu/tree.c:2741
 netlink_release+0x12c0/0x1818 net/netlink/af_netlink.c:828
 __sock_release net/socket.c:653 [inline]
 sock_close+0xb8/0x1fc net/socket.c:1397
 __fput+0x30c/0x7bc fs/file_table.c:321
 ____fput+0x20/0x30 fs/file_table.c:349
 task_work_run+0x230/0x2e0 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x63c/0x1f58 kernel/exit.c:871
 do_group_exit+0x194/0x22c kernel/exit.c:1021
 get_signal+0x14b0/0x159c kernel/signal.c:2874
 do_signal arch/arm64/kernel/signal.c:1249 [inline]
 do_notify_resume+0x3cc/0x3c90 arch/arm64/kernel/signal.c:1302
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 asm_exit_to_user_mode+0x64/0x78 arch/arm64/kernel/entry-common.c:149
 ret_from_fork+0x1c/0x20 arch/arm64/kernel/entry.S:856

The buggy address belongs to the object at ffff00012cf7e000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 12 bytes inside of
 freed 2048-byte region [ffff00012cf7e000, ffff00012cf7e800)

The buggy address belongs to the physical page:
page:0000000071438238 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16cf78
head:0000000071438238 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 05ffc00000010200 ffff0000c0002900 fffffc0004bbd200 dead000000000002
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff00012cf7df00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff00012cf7df80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff00012cf7e000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff00012cf7e080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff00012cf7e100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
list_add corruption. prev is NULL.
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:24!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 9108 Comm: syz-executor.3 Tainted: G    B              6.4.0-rc3-syzkaller-geb0f1697d729 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __list_add_valid+0xcc/0x110 lib/list_debug.c:23
lr : __list_add_valid+0xcc/0x110 lib/list_debug.c:23
sp : ffff8000200e77e0
x29: ffff8000200e77e0 x28: ffff0000d7836014 x27: ffff0000dd6ca418
x26: ffff0000dd6ca410 x25: dfff800000000000 x24: 0000000000000000
x23: 0000000000000000 x22: ffff0000dd6ca3c8 x21: ffff0000d7836000
x20: 1fffe0001bad9483 x19: ffff0000dd6ca000 x18: 1fffe00036848bbe
x17: 0000000000000000 x16: ffff800012381170 x15: 0000000000000002
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000001
x11: 0000000000000001 x10: 0000000000000000 x9 : 4fe89f91d60bd200
x8 : 4fe89f91d60bd200 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000200e70f8 x4 : ffff800015f9e800 x3 : ffff80000835d3ec
x2 : 0000000000000001 x1 : 0000000100000001 x0 : 0000000000000022
Call trace:
 __list_add_valid+0xcc/0x110 lib/list_debug.c:23
 __list_add include/linux/list.h:69 [inline]
 list_add_tail include/linux/list.h:102 [inline]
 gsm_send+0x350/0x604 drivers/tty/n_gsm.c:835
 gsm_command drivers/tty/n_gsm.c:898 [inline]
 gsm_dlci_begin_close drivers/tty/n_gsm.c:2364 [inline]
 gsm_cleanup_mux+0x1a0/0x7f4 drivers/tty/n_gsm.c:3053
 gsm_config drivers/tty/n_gsm.c:3327 [inline]
 gsmld_ioctl+0x13bc/0x221c drivers/tty/n_gsm.c:3733
 tty_ioctl+0x924/0xd8c drivers/tty/tty_io.c:2786
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
Code: d4210000 b003fc20 913f8000 95e49dd5 (d4210000) 
---[ end trace 0000000000000000 ]---