Hello, When fuzzing the Linux kernel driver v6.0-rc4, the following crash was triggered. HEAD commit: 7e18e42e4b280c85b76967a9106a13ca61c16179 git tree: upstream kernel config: https://pastebin.com/raw/xtrgsXP3 C reproducer: https://pastebin.com/raw/w2sdQWYj console output: https://pastebin.com/raw/Yyf7zw2d Basically, in the c reproducer, we use the gadget module to emulate attaching a USB device(vendor id: 0x1bc7, product id: 0x1206, with the midi function) and executing some simple sequence of system calls. To reproduce this crash, we utilize a third-party library to emulate the attaching process: https://github.com/linux-usb-gadgets/libusbgx. Just clone this repository, install it, and compile the c reproducer with ``` gcc crash.c -lusbgx -lconfig -o crash ``` will do the trick. I would appreciate it if you have any idea how to solve this bug. The crash report is as follows: ================================================================== BUG: KASAN: double-free in snd_card_new+0xf9/0x130 sound/core/init.c:182 CPU: 1 PID: 7476 Comm: syz-executor.2 Not tainted 6.0.0-rc4+ #20 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_invalid_free+0x5b/0x160 mm/kasan/report.c:462 ____kasan_slab_free mm/kasan/common.c:356 [inline] __kasan_slab_free+0x179/0x1b0 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 snd_card_new+0xf9/0x130 sound/core/init.c:182 snd_usb_audio_create sound/usb/card.c:621 [inline] usb_audio_probe+0x162a/0x2f10 sound/usb/card.c:797 usb_probe_interface+0x361/0x800 drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:560 [inline] really_probe+0x249/0xa90 drivers/base/dd.c:639 __driver_probe_device+0x1df/0x4d0 drivers/base/dd.c:778 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:808 __device_attach_driver+0x1da/0x2d0 drivers/base/dd.c:936 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427 __device_attach+0x283/0x480 drivers/base/dd.c:1008 proc_ioctl drivers/usb/core/devio.c:2356 [inline] proc_ioctl+0x5b4/0x6e0 drivers/usb/core/devio.c:2307 proc_ioctl_default drivers/usb/core/devio.c:2391 [inline] usbdev_do_ioctl drivers/usb/core/devio.c:2747 [inline] usbdev_ioctl+0x29a3/0x3340 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 RIP: 0033:0x7f0dda8a80fd Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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:00007f0ddaf63bf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f0dda99c340 RCX: 00007f0dda8a80fd RDX: 0000000020000900 RSI: 00000000c0105512 RDI: 0000000000000003 RBP: 00007f0ddaf63c50 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000000d R13: 00007ffeb548e29f R14: 00007ffeb548e440 R15: 00007f0ddaf63d80 </TASK> Allocated by task 7476: 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] snd_card_new+0x78/0x130 sound/core/init.c:176 snd_usb_audio_create sound/usb/card.c:621 [inline] usb_audio_probe+0x162a/0x2f10 sound/usb/card.c:797 usb_probe_interface+0x361/0x800 drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:560 [inline] really_probe+0x249/0xa90 drivers/base/dd.c:639 __driver_probe_device+0x1df/0x4d0 drivers/base/dd.c:778 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:808 __device_attach_driver+0x1da/0x2d0 drivers/base/dd.c:936 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427 __device_attach+0x283/0x480 drivers/base/dd.c:1008 proc_ioctl drivers/usb/core/devio.c:2356 [inline] proc_ioctl+0x5b4/0x6e0 drivers/usb/core/devio.c:2307 proc_ioctl_default drivers/usb/core/devio.c:2391 [inline] usbdev_do_ioctl drivers/usb/core/devio.c:2747 [inline] usbdev_ioctl+0x29a3/0x3340 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 Freed by task 7476: 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 snd_card_do_free sound/core/init.c:605 [inline] release_card_device+0x1af/0x200 sound/core/init.c:145 device_release+0x9f/0x240 drivers/base/core.c:2330 kobject_cleanup lib/kobject.c:673 [inline] kobject_release lib/kobject.c:704 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1be/0x4c0 lib/kobject.c:721 put_device+0x1b/0x30 drivers/base/core.c:3624 snd_card_init+0x973/0xbd0 sound/core/init.c:367 snd_card_new+0xa1/0x130 sound/core/init.c:180 snd_usb_audio_create sound/usb/card.c:621 [inline] usb_audio_probe+0x162a/0x2f10 sound/usb/card.c:797 usb_probe_interface+0x361/0x800 drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:560 [inline] really_probe+0x249/0xa90 drivers/base/dd.c:639 __driver_probe_device+0x1df/0x4d0 drivers/base/dd.c:778 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:808 __device_attach_driver+0x1da/0x2d0 drivers/base/dd.c:936 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427 __device_attach+0x283/0x480 drivers/base/dd.c:1008 proc_ioctl drivers/usb/core/devio.c:2356 [inline] proc_ioctl+0x5b4/0x6e0 drivers/usb/core/devio.c:2307 proc_ioctl_default drivers/usb/core/devio.c:2391 [inline] usbdev_do_ioctl drivers/usb/core/devio.c:2747 [inline] usbdev_ioctl+0x29a3/0x3340 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 ffff888041f54000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 0 bytes inside of 8192-byte region [ffff888041f54000, ffff888041f56000) The buggy address belongs to the physical page: page:ffffea000107d400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x41f50 head:ffffea000107d400 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4fff00000010200(slab|head|node=1|zone=1|lastcpupid=0x7ff) raw: 04fff00000010200 ffffea0001092200 dead000000000004 ffff888011c42280 raw: 0000000000000000 0000000080020002 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 1, tgid 1 (swapper/0), ts 14941420612, free_ts 14728973666 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_page_interleave+0x1e/0x250 mm/mempolicy.c:2103 alloc_pages+0x25f/0x2f0 mm/mempolicy.c:2265 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] slab_alloc mm/slub.c:3251 [inline] __kmalloc+0x388/0x3f0 mm/slub.c:4420 kmalloc_array include/linux/slab.h:640 [inline] fb_show_logo_line drivers/video/fbdev/core/fbmem.c:491 [inline] fb_show_logo+0x1398/0x23c0 drivers/video/fbdev/core/fbmem.c:695 fbcon_switch+0xef7/0x12a0 drivers/video/fbdev/core/fbcon.c:2183 redraw_screen+0x2b9/0x740 drivers/tty/vt/vt.c:1021 con2fb_init_display drivers/video/fbdev/core/fbcon.c:806 [inline] set_con2fb_map+0x798/0xec0 drivers/video/fbdev/core/fbcon.c:865 do_fb_registered drivers/video/fbdev/core/fbcon.c:3012 [inline] fbcon_fb_registered+0x208/0x460 drivers/video/fbdev/core/fbcon.c:3028 do_register_framebuffer drivers/video/fbdev/core/fbmem.c:1696 [inline] register_framebuffer+0x545/0x910 drivers/video/fbdev/core/fbmem.c:1865 __drm_fb_helper_initial_config_and_unlock+0xdc6/0x1350 drivers/gpu/drm/drm_fb_helper.c:1910 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 __unfreeze_partials+0x3f3/0x410 mm/slub.c:2548 qlink_free mm/kasan/quarantine.c:168 [inline] qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187 kasan_quarantine_reduce+0x13d/0x180 mm/kasan/quarantine.c:294 __kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:447 kasan_slab_alloc include/linux/kasan.h:224 [inline] slab_post_alloc_hook+0x4d/0x4f0 mm/slab.h:727 slab_alloc_node mm/slub.c:3243 [inline] slab_alloc mm/slub.c:3251 [inline] __kmem_cache_alloc_lru mm/slub.c:3258 [inline] kmem_cache_alloc+0x151/0x360 mm/slub.c:3268 ptlock_alloc mm/memory.c:5774 [inline] ptlock_init include/linux/mm.h:2261 [inline] pmd_ptlock_init include/linux/mm.h:2347 [inline] pgtable_pmd_page_ctor include/linux/mm.h:2383 [inline] pmd_alloc_one include/asm-generic/pgalloc.h:129 [inline] __pmd_alloc+0xbf/0x5b0 mm/memory.c:5225 pmd_alloc include/linux/mm.h:2211 [inline] __handle_mm_fault+0x856/0x2e00 mm/memory.c:5013 handle_mm_fault+0x322/0xa80 mm/memory.c:5151 faultin_page mm/gup.c:990 [inline] __get_user_pages+0x5be/0x1250 mm/gup.c:1219 __get_user_pages_locked mm/gup.c:1423 [inline] __get_user_pages_remote mm/gup.c:2133 [inline] __get_user_pages_remote+0x196/0x810 mm/gup.c:2109 get_user_pages_remote+0x80/0xc0 mm/gup.c:2206 get_arg_page+0xe4/0x2a0 fs/exec.c:222 copy_string_kernel+0x16d/0x4f0 fs/exec.c:639 Memory state around the buggy address: ffff888041f53f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888041f53f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888041f54000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888041f54080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888041f54100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
