================================================================== BUG: KASAN: use-after-free in gsm_cleanup_mux+0x785/0x800 drivers/tty/n_gsm.c:2487 Read of size 4 at addr ffff888043d4900c by task syz-executor.0/29846 CPU: 0 PID: 29846 Comm: syz-executor.0 Not tainted 6.1.0-rc2-syzkaller-00105-gb229b6ca5abb #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:284 [inline] print_report+0x15e/0x45d mm/kasan/report.c:395 kasan_report+0xbb/0x1f0 mm/kasan/report.c:495 gsm_cleanup_mux+0x785/0x800 drivers/tty/n_gsm.c:2487 gsm_config drivers/tty/n_gsm.c:2752 [inline] gsmld_ioctl+0x52f/0x1060 drivers/tty/n_gsm.c:3113 tty_ioctl+0x741/0x1590 drivers/tty/tty_io.c:2780 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+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fe6f6a8b5a9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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:00007fe6f5dff168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fe6f6bac050 RCX: 00007fe6f6a8b5a9 RDX: 0000000020000040 RSI: 00000000404c4701 RDI: 0000000000000004 RBP: 00007fe6f6ae67b0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe6f6ccfb1f R14: 00007fe6f5dff300 R15: 0000000000022000 Allocated by task 29778: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45 kasan_set_track+0x21/0x30 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:371 [inline] ____kasan_kmalloc mm/kasan/common.c:330 [inline] __kasan_kmalloc+0xa1/0xb0 mm/kasan/common.c:380 kmalloc include/linux/slab.h:576 [inline] kzalloc include/linux/slab.h:712 [inline] gsm_dlci_alloc+0x46/0x480 drivers/tty/n_gsm.c:2060 gsm_activate_mux drivers/tty/n_gsm.c:2534 [inline] gsm_config drivers/tty/n_gsm.c:2776 [inline] gsmld_ioctl+0x7fc/0x1060 drivers/tty/n_gsm.c:3113 tty_ioctl+0x741/0x1590 drivers/tty/tty_io.c:2780 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+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 29841: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45 kasan_set_track+0x21/0x30 mm/kasan/common.c:52 kasan_save_free_info+0x2a/0x40 mm/kasan/generic.c:511 ____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:177 [inline] slab_free_hook mm/slub.c:1724 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1750 slab_free mm/slub.c:3661 [inline] __kmem_cache_free+0xab/0x3b0 mm/slub.c:3674 tty_port_destructor drivers/tty/tty_port.c:296 [inline] kref_put include/linux/kref.h:65 [inline] tty_port_put+0x158/0x1c0 drivers/tty/tty_port.c:311 dlci_put drivers/tty/n_gsm.c:2116 [inline] gsm_dlci_release drivers/tty/n_gsm.c:2149 [inline] gsm_cleanup_mux+0x2f6/0x800 drivers/tty/n_gsm.c:2508 gsm_config drivers/tty/n_gsm.c:2752 [inline] gsmld_ioctl+0x52f/0x1060 drivers/tty/n_gsm.c:3113 tty_ioctl+0x741/0x1590 drivers/tty/tty_io.c:2780 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+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Last potentially related work creation: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45 __kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:481 call_rcu+0x99/0x820 kernel/rcu/tree.c:2798 netlink_release+0xeff/0x1db0 net/netlink/af_netlink.c:815 __sock_release net/socket.c:650 [inline] sock_release+0x87/0x1b0 net/socket.c:678 netlink_kernel_release+0x4b/0x60 net/netlink/af_netlink.c:2107 nfnetlink_net_exit_batch+0x10e/0x320 net/netfilter/nfnetlink.c:781 ops_exit_list+0x125/0x170 net/core/net_namespace.c:174 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:601 process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e4/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 Second to last potentially related work creation: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45 __kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:481 call_rcu+0x99/0x820 kernel/rcu/tree.c:2798 netlink_release+0xeff/0x1db0 net/netlink/af_netlink.c:815 __sock_release+0xcd/0x280 net/socket.c:650 sock_close+0x18/0x20 net/socket.c:1365 __fput+0x27c/0xa90 fs/file_table.c:320 task_work_run+0x16b/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xb35/0x2a20 kernel/exit.c:820 do_group_exit+0xd0/0x2a0 kernel/exit.c:950 get_signal+0x21a1/0x2430 kernel/signal.c:2858 arch_do_signal_or_restart+0x82/0x2300 arch/x86/kernel/signal.c:869 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:296 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff888043d49000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 12 bytes inside of 2048-byte region [ffff888043d49000, ffff888043d49800) The buggy address belongs to the physical page: page:ffffea00010f5200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x43d48 head:ffffea00010f5200 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 dead000000000001 ffff888011842000 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 3654, tgid 3654 (syz-executor.0), ts 139828475845, free_ts 12080707870 prep_new_page mm/page_alloc.c:2538 [inline] get_page_from_freelist+0x10b5/0x2d50 mm/page_alloc.c:4287 __alloc_pages+0x1c7/0x5a0 mm/page_alloc.c:5554 alloc_pages+0x1a6/0x270 mm/mempolicy.c:2285 alloc_slab_page mm/slub.c:1794 [inline] allocate_slab+0x213/0x300 mm/slub.c:1939 new_slab mm/slub.c:1992 [inline] ___slab_alloc+0xa91/0x1400 mm/slub.c:3180 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3279 slab_alloc_node mm/slub.c:3364 [inline] __kmem_cache_alloc_node+0x191/0x3e0 mm/slub.c:3437 __do_kmalloc_node mm/slab_common.c:954 [inline] __kmalloc+0x44/0xc0 mm/slab_common.c:968 kmalloc include/linux/slab.h:581 [inline] kzalloc include/linux/slab.h:712 [inline] ops_init+0x241/0x680 net/core/net_namespace.c:125 setup_net+0x5d1/0xc50 net/core/net_namespace.c:332 copy_net_ns+0x318/0x760 net/core/net_namespace.c:478 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226 ksys_unshare+0x445/0x920 kernel/fork.c:3188 __do_sys_unshare kernel/fork.c:3259 [inline] __se_sys_unshare kernel/fork.c:3257 [inline] __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3257 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1458 [inline] free_pcp_prepare+0x65c/0xd90 mm/page_alloc.c:1508 free_unref_page_prepare mm/page_alloc.c:3386 [inline] free_unref_page+0x19/0x4d0 mm/page_alloc.c:3482 free_contig_range+0xb1/0x180 mm/page_alloc.c:9492 destroy_args+0xa8/0x64c mm/debug_vm_pgtable.c:1031 debug_vm_pgtable+0x2954/0x29e5 mm/debug_vm_pgtable.c:1354 do_one_initcall+0x13d/0x780 init/main.c:1303 do_initcall_level init/main.c:1376 [inline] do_initcalls init/main.c:1392 [inline] do_basic_setup init/main.c:1411 [inline] kernel_init_freeable+0x6ff/0x788 init/main.c:1631 kernel_init+0x1a/0x1d0 init/main.c:1519 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 Memory state around the buggy address: ffff888043d48f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888043d48f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888043d49000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888043d49080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888043d49100: fb 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