Hello, syzbot found the following issue on: HEAD commit: a1f92694 Add linux-next specific files for 20210518 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=12cb6184300000 kernel config: https://syzkaller.appspot.com/x/.config?x=d612e75ffd53a6d3 dashboard link: https://syzkaller.appspot.com/bug?extid=19c5a4b75931e8d63aab syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13f87f20300000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f82d34300000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+19c5a4b75931e8d63aab@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== BUG: KASAN: use-after-free in v4l2_ioctl+0x1f1/0x250 drivers/media/v4l2-core/v4l2-dev.c:364 Read of size 8 at addr ffff88801dc54398 by task v4l_id/25000 CPU: 0 PID: 25000 Comm: v4l_id Not tainted 5.13.0-rc2-next-20210518-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x13e/0x1d6 lib/dump_stack.c:129 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233 __kasan_report mm/kasan/report.c:419 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:436 v4l2_ioctl+0x1f1/0x250 drivers/media/v4l2-core/v4l2-dev.c:364 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl fs/ioctl.c:1055 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055 do_syscall_64+0x31/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f30112bb017 Code: 00 00 00 48 8b 05 81 7e 2b 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 51 7e 2b 00 f7 d8 64 89 01 48 RSP: 002b:00007ffcfc119d68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f30112bb017 RDX: 00007ffcfc119d70 RSI: 0000000080685600 RDI: 0000000000000003 RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 000055f2227cb8d0 R13: 00007ffcfc119ed0 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 12321: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:431 [inline] ____kasan_kmalloc mm/kasan/common.c:510 [inline] ____kasan_kmalloc mm/kasan/common.c:469 [inline] __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:519 kmalloc include/linux/slab.h:590 [inline] kzalloc include/linux/slab.h:720 [inline] stk_camera_probe+0x7d/0xc50 drivers/media/usb/stkwebcam/stk-webcam.c:1281 usb_probe_interface+0x315/0x7f0 drivers/usb/core/driver.c:396 really_probe+0x291/0xf60 drivers/base/dd.c:576 driver_probe_device+0x298/0x410 drivers/base/dd.c:763 __device_attach_driver+0x203/0x2c0 drivers/base/dd.c:870 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:431 __device_attach+0x228/0x4a0 drivers/base/dd.c:938 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491 device_add+0xbe0/0x2100 drivers/base/core.c:3320 usb_set_configuration+0x113f/0x1910 drivers/usb/core/message.c:2164 usb_generic_driver_probe+0xba/0x100 drivers/usb/core/generic.c:238 usb_probe_device+0xd9/0x2c0 drivers/usb/core/driver.c:293 really_probe+0x291/0xf60 drivers/base/dd.c:576 driver_probe_device+0x298/0x410 drivers/base/dd.c:763 __device_attach_driver+0x203/0x2c0 drivers/base/dd.c:870 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:431 __device_attach+0x228/0x4a0 drivers/base/dd.c:938 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491 device_add+0xbe0/0x2100 drivers/base/core.c:3320 usb_new_device.cold+0x721/0x1058 drivers/usb/core/hub.c:2556 hub_port_connect drivers/usb/core/hub.c:5276 [inline] hub_port_connect_change drivers/usb/core/hub.c:5416 [inline] port_event drivers/usb/core/hub.c:5562 [inline] hub_event+0x2357/0x4330 drivers/usb/core/hub.c:5644 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Freed by task 16814: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357 ____kasan_slab_free mm/kasan/common.c:363 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:371 kasan_slab_free include/linux/kasan.h:212 [inline] slab_free_hook mm/slub.c:1623 [inline] slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1648 slab_free mm/slub.c:3208 [inline] kfree+0xeb/0x650 mm/slub.c:4274 usb_unbind_interface+0x1d8/0x8d0 drivers/usb/core/driver.c:458 __device_release_driver+0x3bd/0x6f0 drivers/base/dd.c:1181 device_release_driver_internal drivers/base/dd.c:1212 [inline] device_release_driver+0x26/0x40 drivers/base/dd.c:1235 bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:533 device_del+0x502/0xd40 drivers/base/core.c:3508 usb_disable_device+0x35b/0x7b0 drivers/usb/core/message.c:1413 usb_disconnect.cold+0x27a/0x78e drivers/usb/core/hub.c:2219 hub_port_connect drivers/usb/core/hub.c:5127 [inline] hub_port_connect_change drivers/usb/core/hub.c:5416 [inline] port_event drivers/usb/core/hub.c:5562 [inline] hub_event+0x1c9c/0x4330 drivers/usb/core/hub.c:5644 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 The buggy address belongs to the object at ffff88801dc54000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 920 bytes inside of 4096-byte region [ffff88801dc54000, ffff88801dc55000) The buggy address belongs to the page: page:ffffea0000771400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1dc50 head:ffffea0000771400 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 0000000100000001 ffff888011042140 raw: 0000000000000000 0000000000040004 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 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 11559, ts 1619924100847, free_ts 1619644095689 prep_new_page mm/page_alloc.c:2377 [inline] get_page_from_freelist+0x125c/0x2ed0 mm/page_alloc.c:4038 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5239 alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2272 alloc_slab_page mm/slub.c:1686 [inline] allocate_slab+0x2c2/0x4c0 mm/slub.c:1826 new_slab mm/slub.c:1889 [inline] new_slab_objects mm/slub.c:2635 [inline] ___slab_alloc+0x4ba/0x820 mm/slub.c:2798 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2838 slab_alloc_node mm/slub.c:2920 [inline] slab_alloc mm/slub.c:2962 [inline] __kmalloc+0x312/0x330 mm/slub.c:4112 kmalloc include/linux/slab.h:595 [inline] tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_perm+0x21b/0x400 security/tomoyo/file.c:822 security_inode_getattr+0xcf/0x140 security/security.c:1332 vfs_getattr fs/stat.c:139 [inline] vfs_statx+0x164/0x390 fs/stat.c:207 vfs_fstatat fs/stat.c:225 [inline] vfs_lstat include/linux/fs.h:3384 [inline] __do_sys_newlstat+0x91/0x110 fs/stat.c:380 do_syscall_64+0x31/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1305 [inline] __free_pages_ok+0x4cb/0xf30 mm/page_alloc.c:1586 qlink_free mm/kasan/quarantine.c:146 [inline] qlist_free_all+0x5a/0xc0 mm/kasan/quarantine.c:165 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:272 __kasan_slab_alloc+0x8e/0xa0 mm/kasan/common.c:441 kasan_slab_alloc include/linux/kasan.h:236 [inline] slab_post_alloc_hook mm/slab.h:512 [inline] slab_alloc_node mm/slub.c:2954 [inline] slab_alloc mm/slub.c:2962 [inline] kmem_cache_alloc+0x285/0x4a0 mm/slub.c:2967 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138 getname_flags include/linux/audit.h:319 [inline] getname fs/namei.c:209 [inline] __do_sys_unlink fs/namei.c:4139 [inline] __se_sys_unlink fs/namei.c:4137 [inline] __x64_sys_unlink+0xb1/0x100 fs/namei.c:4137 do_syscall_64+0x31/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae Memory state around the buggy address: ffff88801dc54280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801dc54300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88801dc54380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88801dc54400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801dc54480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb 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