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BUG: KASAN: slab-use-after-free in gsm_cleanup_mux+0x799/0x810 drivers/tty/n_gsm.c:3052
Read of size 4 at addr ffff88807cdd400c by task syz-executor427/5096

CPU: 0 PID: 5096 Comm: syz-executor427 Not tainted 6.4.0-rc3-syzkaller-00291-g4e893b5aa4ac #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:351
 print_report mm/kasan/report.c:462 [inline]
 kasan_report+0x11c/0x130 mm/kasan/report.c:572
 gsm_cleanup_mux+0x799/0x810 drivers/tty/n_gsm.c:3052
 gsm_config drivers/tty/n_gsm.c:3327 [inline]
 gsmld_ioctl+0x4cd/0x1850 drivers/tty/n_gsm.c:3733
 tty_ioctl+0x80b/0x16e0 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]
 __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f3af41a8c49
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3af4139318 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f3af42304d8 RCX: 00007f3af41a8c49
RDX: 0000000020000040 RSI: 00000000404c4701 RDI: 0000000000000004
RBP: 00007f3af42304d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3af41fe07c
R13: 00007ffd74d0e68f R14: 00007f3af4139400 R15: 0000000000022000
 </TASK>

Allocated by task 5095:
 kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 ____kasan_kmalloc mm/kasan/common.c:333 [inline]
 __kasan_kmalloc+0xa2/0xb0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:559 [inline]
 kzalloc include/linux/slab.h:680 [inline]
 gsm_dlci_alloc+0x46/0x7d0 drivers/tty/n_gsm.c:2618
 gsm_activate_mux drivers/tty/n_gsm.c:3100 [inline]
 gsm_config drivers/tty/n_gsm.c:3355 [inline]
 gsmld_ioctl+0x846/0x1850 drivers/tty/n_gsm.c:3733
 tty_ioctl+0x80b/0x16e0 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]
 __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5095:
 kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:521
 ____kasan_slab_free mm/kasan/common.c:236 [inline]
 ____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
 kasan_slab_free include/linux/kasan.h:162 [inline]
 slab_free_hook mm/slub.c:1781 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1807
 slab_free mm/slub.c:3786 [inline]
 __kmem_cache_free+0xaf/0x2d0 mm/slub.c:3799
 tty_port_destructor drivers/tty/tty_port.c:296 [inline]
 kref_put include/linux/kref.h:65 [inline]
 tty_port_put+0x15c/0x1c0 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+0x30a/0x810 drivers/tty/n_gsm.c:3074
 gsm_config drivers/tty/n_gsm.c:3327 [inline]
 gsmld_ioctl+0x4cd/0x1850 drivers/tty/n_gsm.c:3733
 tty_ioctl+0x80b/0x16e0 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]
 __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88807cdd4000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 12 bytes inside of
 freed 2048-byte region [ffff88807cdd4000, ffff88807cdd4800)

The buggy address belongs to the physical page:
page:ffffea0001f37400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7cdd0
head:ffffea0001f37400 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000010200 ffff888012442000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5093, tgid 5091 (syz-executor427), ts 90151581802, free_ts 90148267618
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2db/0x350 mm/page_alloc.c:1731
 prep_new_page mm/page_alloc.c:1738 [inline]
 get_page_from_freelist+0xf41/0x2c00 mm/page_alloc.c:3502
 __alloc_pages+0x1cb/0x4a0 mm/page_alloc.c:4768
 alloc_pages+0x1aa/0x270 mm/mempolicy.c:2279
 alloc_slab_page mm/slub.c:1851 [inline]
 allocate_slab+0x25f/0x390 mm/slub.c:1998
 new_slab mm/slub.c:2051 [inline]
 ___slab_alloc+0xa91/0x1400 mm/slub.c:3192
 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3291
 __slab_alloc_node mm/slub.c:3344 [inline]
 slab_alloc_node mm/slub.c:3441 [inline]
 __kmem_cache_alloc_node+0x136/0x320 mm/slub.c:3490
 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1057
 kmalloc include/linux/slab.h:559 [inline]
 kzalloc include/linux/slab.h:680 [inline]
 tty_register_device_attr+0x220/0x7d0 drivers/tty/tty_io.c:3235
 gsm_register_devices drivers/tty/n_gsm.c:653 [inline]
 gsm_activate_mux drivers/tty/n_gsm.c:3109 [inline]
 gsm_config drivers/tty/n_gsm.c:3355 [inline]
 gsmld_ioctl+0x97e/0x1850 drivers/tty/n_gsm.c:3733
 tty_ioctl+0x80b/0x16e0 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]
 __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1302 [inline]
 free_unref_page_prepare+0x62e/0xcb0 mm/page_alloc.c:2564
 free_unref_page+0x33/0x370 mm/page_alloc.c:2659
 __folio_put_large mm/swap.c:119 [inline]
 __folio_put+0x109/0x140 mm/swap.c:127
 folio_put include/linux/mm.h:1430 [inline]
 put_page+0x21b/0x280 include/linux/mm.h:1499
 page_to_skb+0x816/0xa10 drivers/net/virtio_net.c:545
 receive_mergeable drivers/net/virtio_net.c:1344 [inline]
 receive_buf+0x11b7/0x61b0 drivers/net/virtio_net.c:1479
 virtnet_receive drivers/net/virtio_net.c:1777 [inline]
 virtnet_poll+0x742/0x14b0 drivers/net/virtio_net.c:1849
 __napi_poll+0xb7/0x6f0 net/core/dev.c:6496
 napi_poll net/core/dev.c:6563 [inline]
 net_rx_action+0x8a9/0xcb0 net/core/dev.c:6696
 __do_softirq+0x1d4/0x905 kernel/softirq.c:571

Memory state around the buggy address:
 ffff88807cdd3f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88807cdd3f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88807cdd4000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88807cdd4080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807cdd4100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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