bisecting fixing commit since e4e453434a199cdfa1e1e5cc723d8736f522354a building syzkaller on 1ba81399e2d03b53a7e631c4ab05f25af1fb1911 testing commit e4e453434a199cdfa1e1e5cc723d8736f522354a compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: b406e49db67074853b023b3ea50338bfaa091ea93478ee3cdf1a2bb6f1eec48e run #0: crashed: KASAN: use-after-free Read in v4l2_fh_init run #1: crashed: KASAN: use-after-free Read in v4l2_fh_init run #2: crashed: KASAN: use-after-free Read in v4l2_fh_init run #3: crashed: KASAN: use-after-free Read in v4l2_fh_init run #4: crashed: KASAN: use-after-free Read in v4l2_fh_init run #5: crashed: KASAN: use-after-free Read in v4l2_fh_init run #6: crashed: KASAN: use-after-free Read in v4l2_fh_init run #7: crashed: KASAN: use-after-free Read in v4l2_fh_init run #8: crashed: KASAN: use-after-free Read in v4l2_fh_init run #9: crashed: KASAN: use-after-free Read in v4l2_fh_init run #10: crashed: KASAN: use-after-free Read in v4l2_fh_init run #11: crashed: KASAN: use-after-free Read in v4l2_fh_init run #12: crashed: KASAN: use-after-free Read in v4l2_fh_init run #13: crashed: KASAN: use-after-free Read in v4l2_fh_init run #14: crashed: KASAN: use-after-free Read in v4l2_fh_init run #15: crashed: KASAN: use-after-free Read in v4l2_fh_init run #16: crashed: KASAN: use-after-free Read in v4l2_fh_init run #17: crashed: KASAN: use-after-free Read in v4l2_fh_init run #18: crashed: KASAN: use-after-free Read in v4l2_fh_init run #19: crashed: KASAN: null-ptr-deref Write in v4l2_prio_open testing current HEAD f0e18b03fcafd8344539101f564ae358950ae892 testing commit f0e18b03fcafd8344539101f564ae358950ae892 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 00f14b6d30eecc1e7de06fa34fefad3a98ba0bef0c4b728e5cdeab574d980c15 all runs: crashed: KASAN: use-after-free Read in v4l2_fh_init revisions tested: 2, total time: 20m1.084835744s (build: 11m58.346334058s, test: 7m20.52153953s) the crash still happens on HEAD commit msg: Merge tag 'x86_urgent_for_v5.17_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip crash: KASAN: use-after-free Read in v4l2_fh_init ================================================================== BUG: KASAN: use-after-free in v4l2_fh_init+0x274/0x2c0 drivers/media/v4l2-core/v4l2-fh.c:25 Read of size 8 at addr ffff8880625ec8c0 by task v4l_id/4764 CPU: 0 PID: 4764 Comm: v4l_id Not tainted 5.17.0-rc7-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+0x57/0x7d lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255 __kasan_report mm/kasan/report.c:442 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 v4l2_fh_init+0x274/0x2c0 drivers/media/v4l2-core/v4l2-fh.c:25 v4l2_fh_open+0x78/0xb0 drivers/media/v4l2-core/v4l2-fh.c:63 em28xx_v4l2_open+0xd6/0x430 drivers/media/usb/em28xx/em28xx-video.c:2163 v4l2_open+0x1e3/0x370 drivers/media/v4l2-core/v4l2-dev.c:427 chrdev_open+0x20f/0x650 fs/char_dev.c:414 do_dentry_open+0x429/0x1050 fs/open.c:824 do_open fs/namei.c:3476 [inline] path_openat+0x9ea/0x2390 fs/namei.c:3609 do_filp_open+0x199/0x3d0 fs/namei.c:3636 do_sys_openat2+0x11e/0x400 fs/open.c:1214 do_sys_open fs/open.c:1230 [inline] __do_sys_openat fs/open.c:1246 [inline] __se_sys_openat fs/open.c:1241 [inline] __x64_sys_openat+0x11b/0x1d0 fs/open.c:1241 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+0x44/0xae RIP: 0033:0x7f67b6553697 Code: 25 00 00 41 00 3d 00 00 41 00 74 37 64 8b 04 25 18 00 00 00 85 c0 75 5b 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 85 00 00 00 48 83 c4 68 5d 41 5c c3 0f 1f RSP: 002b:00007ffe6d5e8c80 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 000055f9e48aac40 RCX: 00007f67b6553697 RDX: 0000000000000000 RSI: 00007ffe6d5eaf1e RDI: 00000000ffffff9c RBP: 00007ffe6d5eaf1e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 The buggy address belongs to the page: page:ffffea0001897b00 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x625ec flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 ffffea00018cb108 ffff8880b9e3fff0 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as freed page last allocated via order 2, migratetype Unmovable, gfp_mask 0x140dc0(GFP_USER|__GFP_COMP|__GFP_ZERO), pid 4137, ts 117777884557, free_ts 117933558787 prep_new_page mm/page_alloc.c:2434 [inline] get_page_from_freelist+0xa6f/0x2f10 mm/page_alloc.c:4165 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389 kmalloc_order+0x34/0xf0 mm/slab_common.c:944 kmalloc_order_trace+0x14/0x120 mm/slab_common.c:960 kmalloc_large include/linux/slab.h:510 [inline] kmalloc include/linux/slab.h:574 [inline] kzalloc include/linux/slab.h:714 [inline] em28xx_v4l2_init drivers/media/usb/em28xx/em28xx-video.c:2542 [inline] em28xx_v4l2_init.cold+0x65/0x2d3f drivers/media/usb/em28xx/em28xx-video.c:2520 em28xx_init_extension+0x106/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1126 process_one_work+0x879/0x1410 kernel/workqueue.c:2307 process_scheduled_works kernel/workqueue.c:2370 [inline] worker_thread+0x6ef/0xf60 kernel/workqueue.c:2459 kthread+0x299/0x340 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1352 [inline] free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404 free_unref_page_prepare mm/page_alloc.c:3325 [inline] free_unref_page+0x19/0x690 mm/page_alloc.c:3404 em28xx_v4l2_init drivers/media/usb/em28xx/em28xx-video.c:2911 [inline] em28xx_v4l2_init.cold+0x21f/0x2d3f drivers/media/usb/em28xx/em28xx-video.c:2520 em28xx_init_extension+0x106/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1126 process_one_work+0x879/0x1410 kernel/workqueue.c:2307 process_scheduled_works kernel/workqueue.c:2370 [inline] worker_thread+0x6ef/0xf60 kernel/workqueue.c:2459 kthread+0x299/0x340 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Memory state around the buggy address: ffff8880625ec780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8880625ec800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff8880625ec880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8880625ec900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8880625ec980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ==================================================================