================================================================== BUG: KASAN: slab-use-after-free in dvb_device_open+0x36a/0x3b0 drivers/media/dvb-core/dvbdev.c:99 Read of size 8 at addr ffff888029edfc18 by task syz.1.5478/20026 CPU: 1 UID: 0 PID: 20026 Comm: syz.1.5478 Not tainted 6.15.0-rc4-syzkaller-00291-g2a239ffbebb5 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 dvb_device_open+0x36a/0x3b0 drivers/media/dvb-core/dvbdev.c:99 chrdev_open+0x231/0x6a0 fs/char_dev.c:414 do_dentry_open+0x741/0x1c10 fs/open.c:956 vfs_open+0x82/0x3f0 fs/open.c:1086 do_open fs/namei.c:3880 [inline] path_openat+0x1e5e/0x2d40 fs/namei.c:4039 do_filp_open+0x20b/0x470 fs/namei.c:4066 do_sys_openat2+0x11b/0x1d0 fs/open.c:1429 do_sys_open fs/open.c:1444 [inline] __do_sys_openat fs/open.c:1460 [inline] __se_sys_openat fs/open.c:1455 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1455 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff5f9b8e969 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff5faa45038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007ff5f9db5fa0 RCX: 00007ff5f9b8e969 RDX: 0000000000000001 RSI: 0000200000000000 RDI: ffffffffffffff9c RBP: 00007ff5f9c10ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ff5f9db5fa0 R15: 00007ffe19058ca8 Allocated by task 19807: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __do_kmalloc_node mm/slub.c:4327 [inline] __kmalloc_noprof+0x223/0x510 mm/slub.c:4339 kmalloc_noprof include/linux/slab.h:909 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] new_dir fs/proc/proc_sysctl.c:963 [inline] get_subdir fs/proc/proc_sysctl.c:1007 [inline] sysctl_mkdir_p fs/proc/proc_sysctl.c:1317 [inline] __register_sysctl_table+0xea2/0x1900 fs/proc/proc_sysctl.c:1392 mpls_dev_sysctl_register+0x185/0x2a0 net/mpls/af_mpls.c:1405 mpls_add_dev net/mpls/af_mpls.c:1460 [inline] mpls_dev_notify+0x4ab/0xa20 net/mpls/af_mpls.c:1600 notifier_call_chain+0xb9/0x410 kernel/notifier.c:85 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2176 call_netdevice_notifiers_extack net/core/dev.c:2214 [inline] call_netdevice_notifiers net/core/dev.c:2228 [inline] register_netdevice+0x182e/0x2270 net/core/dev.c:11047 register_netdev+0x34/0x50 net/core/dev.c:11126 vti6_init_net+0x28f/0x490 net/ipv6/ip6_vti.c:1158 ops_init+0x1df/0x5f0 net/core/net_namespace.c:138 setup_net+0x21e/0x850 net/core/net_namespace.c:364 copy_net_ns+0x2a6/0x5f0 net/core/net_namespace.c:518 create_new_namespaces+0x3ea/0xad0 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc0/0x1f0 kernel/nsproxy.c:228 ksys_unshare+0x45b/0xa40 kernel/fork.c:3375 __do_sys_unshare kernel/fork.c:3446 [inline] __se_sys_unshare kernel/fork.c:3444 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:3444 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 1108: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2380 [inline] slab_free_freelist_hook mm/slub.c:2409 [inline] slab_free_bulk mm/slub.c:4666 [inline] kmem_cache_free_bulk.part.0+0x38d/0x7f0 mm/slub.c:5243 kfree_bulk include/linux/slab.h:794 [inline] kvfree_rcu_bulk+0x1bb/0x1f0 mm/slab_common.c:1516 kvfree_rcu_drain_ready mm/slab_common.c:1699 [inline] kfree_rcu_monitor+0x1d0/0x2f0 mm/slab_common.c:1772 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Last potentially related work creation: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_record_aux_stack+0xb8/0xd0 mm/kasan/generic.c:548 kvfree_call_rcu+0x76/0x470 mm/slab_common.c:1962 drop_sysctl_table+0x355/0x5f0 fs/proc/proc_sysctl.c:1518 unregister_sysctl_table fs/proc/proc_sysctl.c:1539 [inline] unregister_sysctl_table+0x41/0x60 fs/proc/proc_sysctl.c:1531 mpls_dev_sysctl_unregister net/mpls/af_mpls.c:1429 [inline] mpls_dev_notify+0x70c/0xa20 net/mpls/af_mpls.c:1641 notifier_call_chain+0xb9/0x410 kernel/notifier.c:85 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2176 call_netdevice_notifiers_extack net/core/dev.c:2214 [inline] call_netdevice_notifiers net/core/dev.c:2228 [inline] unregister_netdevice_many_notify+0xf9a/0x26f0 net/core/dev.c:11982 cleanup_net+0x596/0xb30 net/core/net_namespace.c:649 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 The buggy address belongs to the object at ffff888029edfc00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 24 bytes inside of freed 256-byte region [ffff888029edfc00, ffff888029edfd00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29ede head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801b441b40 ffffea00018e9780 0000000000000005 raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801b441b40 ffffea00018e9780 0000000000000005 head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 head: 00fff00000000001 ffffea0000a7b781 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 24761581498, free_ts 0 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1718 prep_new_page mm/page_alloc.c:1726 [inline] get_page_from_freelist+0x135c/0x3920 mm/page_alloc.c:3688 __alloc_frozen_pages_noprof+0x263/0x23a0 mm/page_alloc.c:4970 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2301 alloc_slab_page mm/slub.c:2450 [inline] allocate_slab mm/slub.c:2618 [inline] new_slab+0x244/0x340 mm/slub.c:2672 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3858 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3948 __slab_alloc_node mm/slub.c:4023 [inline] slab_alloc_node mm/slub.c:4184 [inline] __kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4353 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] bus_add_driver+0x92/0x690 drivers/base/bus.c:662 driver_register+0x15c/0x4b0 drivers/base/driver.c:249 usb_register_driver+0x216/0x4d0 drivers/usb/core/driver.c:1078 do_one_initcall+0x120/0x6e0 init/main.c:1257 do_initcall_level init/main.c:1319 [inline] do_initcalls init/main.c:1335 [inline] do_basic_setup init/main.c:1354 [inline] kernel_init_freeable+0x5c2/0x900 init/main.c:1567 kernel_init+0x1c/0x2b0 init/main.c:1457 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 page_owner free stack trace missing Memory state around the buggy address: ffff888029edfb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888029edfb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888029edfc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888029edfc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888029edfd00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================