When I used fuzz testing to test Linux kernel 6.0.0-rc6, the kernel triggered the following error: HEAD commit: 521a547ced6477c54b4b0cc206000406c221b4d6 git tree: upstream kernel config: https://pastebin.com/raw/hekxU61F console log: https://pastebin.com/raw/YmeXN9F0 It seems that the fuzzer failed to extract any C reproducer, but I would so appreciate it if you have any idea how to solve this bug. ================================================================== BUG: KASAN: use-after-free in filp_close+0x13f/0x160 fs/open.c:1420 Read of size 8 at addr ffff888024d5b078 by task syz-executor.7/12532 CPU: 0 PID: 12532 Comm: syz-executor.7 Not tainted 6.0.0-rc6+ #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: <TASK> __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:317 [inline] print_report.cold+0xe5/0x66d mm/kasan/report.c:433 kasan_report+0x8a/0x1b0 mm/kasan/report.c:495 filp_close+0x13f/0x160 fs/open.c:1420 close_fd+0x76/0xa0 fs/file.c:664 __do_sys_close fs/open.c:1440 [inline] __se_sys_close fs/open.c:1438 [inline] __x64_sys_close+0x2f/0xa0 fs/open.c:1438 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f034163f60b Code: 03 00 00 00 0f 05 48 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 2f 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44 RSP: 002b:00007ffe3a4724e0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 00007f034163f60b RDX: 0000001b2e120000 RSI: 0000001b2e128c00 RDI: 0000000000000006 RBP: 00007f034179dd4c R08: 0000000000000000 R09: 000000003ac8e423 R10: 0000000000000000 R11: 0000000000000293 R12: 00000000000699df R13: 00007ffe3a472620 R14: 00007f034179c4ec R15: 000000000006981e </TASK> Allocated by task 10844: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:437 [inline] ____kasan_kmalloc mm/kasan/common.c:516 [inline] ____kasan_kmalloc mm/kasan/common.c:475 [inline] __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:525 kasan_kmalloc include/linux/kasan.h:234 [inline] __kmalloc+0x1da/0x3f0 mm/slub.c:4424 kmalloc include/linux/slab.h:605 [inline] kzalloc include/linux/slab.h:733 [inline] tomoyo_init_log+0x1254/0x1eb0 security/tomoyo/audit.c:275 tomoyo_supervisor+0x2e7/0xe30 security/tomoyo/common.c:2088 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline] tomoyo_path_permission security/tomoyo/file.c:587 [inline] tomoyo_path_permission+0x270/0x3a0 security/tomoyo/file.c:573 tomoyo_path_perm+0x2fc/0x420 security/tomoyo/file.c:838 tomoyo_path_unlink+0x8e/0xd0 security/tomoyo/tomoyo.c:149 security_path_unlink+0xd7/0x150 security/security.c:1173 do_unlinkat+0x36c/0x660 fs/namei.c:4293 __do_sys_unlink fs/namei.c:4345 [inline] __se_sys_unlink fs/namei.c:4343 [inline] __x64_sys_unlink+0x3e/0x50 fs/namei.c:4343 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 12535: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:45 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:367 [inline] ____kasan_slab_free mm/kasan/common.c:329 [inline] __kasan_slab_free+0x11d/0x1b0 mm/kasan/common.c:375 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1754 [inline] slab_free_freelist_hook mm/slub.c:1780 [inline] slab_free mm/slub.c:3534 [inline] kfree+0xe9/0x650 mm/slub.c:4562 dvb_free_device drivers/media/dvb-core/dvbdev.c:572 [inline] dvb_free_device drivers/media/dvb-core/dvbdev.c:567 [inline] dvb_unregister_device+0x3f/0x60 drivers/media/dvb-core/dvbdev.c:581 dvb_dmxdev_release+0x1c9/0x630 drivers/media/dvb-core/dmxdev.c:1462 ttusb_disconnect+0x144/0x260 drivers/media/usb/ttusb-budget/dvb-ttusb-budget.c:1731 usb_unbind_interface+0x1bd/0x890 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:550 [inline] device_remove+0x11f/0x170 drivers/base/dd.c:542 __device_release_driver drivers/base/dd.c:1249 [inline] device_release_driver_internal+0x1a7/0x360 drivers/base/dd.c:1275 usb_driver_release_interface+0x102/0x180 drivers/usb/core/driver.c:627 usb_forced_unbind_intf+0x48/0xa0 drivers/usb/core/driver.c:1118 usb_reset_device+0x439/0xac0 drivers/usb/core/hub.c:6113 proc_resetdevice drivers/usb/core/devio.c:1514 [inline] usbdev_do_ioctl drivers/usb/core/devio.c:2655 [inline] usbdev_ioctl+0x1e70/0x3340 drivers/usb/core/devio.c:2807 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+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff888024d5b000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 120 bytes inside of 512-byte region [ffff888024d5b000, ffff888024d5b200) The buggy address belongs to the physical page: page:ffffea0000935600 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888024d58400 pfn:0x24d58 head:ffffea0000935600 order:2 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 ffffea0000789108 ffffea0000787108 ffff888011c42c80 raw: ffff888024d58400 0000000000100008 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 0, tgid 0 (swapper/0), ts 378270268280, free_ts 371843614843 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook mm/page_alloc.c:2525 [inline] prep_new_page+0x2c6/0x350 mm/page_alloc.c:2532 get_page_from_freelist+0xae9/0x3a80 mm/page_alloc.c:4283 __alloc_pages+0x321/0x710 mm/page_alloc.c:5515 alloc_pages+0x117/0x2f0 mm/mempolicy.c:2270 alloc_slab_page mm/slub.c:1824 [inline] allocate_slab mm/slub.c:1969 [inline] new_slab+0x246/0x3a0 mm/slub.c:2029 ___slab_alloc+0xa50/0x1060 mm/slub.c:3031 __slab_alloc.isra.0+0x4d/0xa0 mm/slub.c:3118 slab_alloc_node mm/slub.c:3209 [inline] __kmalloc_node_track_caller+0x2ec/0x370 mm/slub.c:4955 kmalloc_reserve+0x32/0xd0 net/core/skbuff.c:362 __alloc_skb+0x11a/0x320 net/core/skbuff.c:434 alloc_skb include/linux/skbuff.h:1257 [inline] ndisc_alloc_skb+0x134/0x330 net/ipv6/ndisc.c:421 ndisc_send_rs+0x37f/0x6f0 net/ipv6/ndisc.c:702 addrconf_rs_timer+0x415/0x740 net/ipv6/addrconf.c:3931 call_timer_fn+0x1a0/0x6b0 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers.part.0+0x69c/0xad0 kernel/time/timer.c:1790 __run_timers kernel/time/timer.c:1768 [inline] run_timer_softirq+0xb6/0x1d0 kernel/time/timer.c:1803 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1449 [inline] free_pcp_prepare+0x5ab/0xd00 mm/page_alloc.c:1499 free_unref_page_prepare mm/page_alloc.c:3380 [inline] free_unref_page+0x19/0x410 mm/page_alloc.c:3476 __stack_depot_save+0x1ef/0x530 lib/stackdepot.c:489 kasan_save_stack+0x2e/0x40 mm/kasan/common.c:39 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:437 [inline] ____kasan_kmalloc mm/kasan/common.c:516 [inline] ____kasan_kmalloc mm/kasan/common.c:475 [inline] __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:525 kasan_kmalloc include/linux/kasan.h:234 [inline] kmem_cache_alloc_trace+0x19b/0x380 mm/slub.c:3284 kmalloc include/linux/slab.h:600 [inline] usb_control_msg+0xb9/0x4a0 drivers/usb/core/message.c:143 get_port_status drivers/usb/core/hub.c:581 [inline] hub_ext_port_status+0x125/0x460 drivers/usb/core/hub.c:598 usb_hub_port_status drivers/usb/core/hub.c:620 [inline] hub_port_wait_reset drivers/usb/core/hub.c:2865 [inline] hub_port_reset+0x2e0/0x1ac0 drivers/usb/core/hub.c:2986 hub_port_init+0x186/0x34d0 drivers/usb/core/hub.c:4703 hub_port_connect drivers/usb/core/hub.c:5282 [inline] hub_port_connect_change drivers/usb/core/hub.c:5497 [inline] port_event drivers/usb/core/hub.c:5653 [inline] hub_event+0x21b6/0x4260 drivers/usb/core/hub.c:5735 process_one_work+0x9c7/0x1650 kernel/workqueue.c:2289 worker_thread+0x623/0x1070 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 Memory state around the buggy address: ffff888024d5af00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888024d5af80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888024d5b000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888024d5b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888024d5b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
