bisecting fixing commit since 4010a528219e01dd02e768b22168f7f0e78365ce building syzkaller on 9a4781d43abfb86fe8521cb6fb084519e237454c testing commit 4010a528219e01dd02e768b22168f7f0e78365ce compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.1 kernel signature: 627d63bb5af390af3186a85f4cc3059108a363090c5ee4c1c4719ed10bf3c2af all runs: crashed: KASAN: use-after-free Read in v4l2_fh_init testing current HEAD 3f5ad13cb012939e1797ec9cdf43941c169216d2 testing commit 3f5ad13cb012939e1797ec9cdf43941c169216d2 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.1 kernel signature: 3dc3f8cbc46fbb095c1a9b863d346a9723b8bb1d1f7b776cf9b57b38ceee3cf4 all runs: crashed: KASAN: use-after-free Read in v4l2_fh_init revisions tested: 2, total time: 20m21.721120847s (build: 12m30.006948997s, test: 7m26.341171893s) the crash still happens on HEAD commit msg: Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi 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 ffff88803d4788f8 by task v4l_id/10453 CPU: 0 PID: 10453 Comm: v4l_id Not tainted 5.14.0-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:105 print_address_description.constprop.0.cold+0x6c/0x2d6 mm/kasan/report.c:233 __kasan_report mm/kasan/report.c:419 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:436 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+0x42a/0xfc0 fs/open.c:826 do_open fs/namei.c:3374 [inline] path_openat+0x9ec/0x22c0 fs/namei.c:3507 do_filp_open+0x199/0x3d0 fs/namei.c:3534 do_sys_openat2+0x11e/0x360 fs/open.c:1204 do_sys_open fs/open.c:1220 [inline] __do_sys_open fs/open.c:1228 [inline] __se_sys_open fs/open.c:1224 [inline] __x64_sys_open+0xfd/0x1a0 fs/open.c:1224 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: 0033:0x7f49146bc840 Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24 RSP: 002b:00007ffee4c356c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007ffee4c35838 RCX: 00007f49146bc840 RDX: 00007f49146a8ea0 RSI: 0000000000000000 RDI: 00007ffee4c36f1e RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 000055ac556318d0 R13: 00007ffee4c35830 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 10368: 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:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] ____kasan_kmalloc mm/kasan/common.c:472 [inline] __kasan_kmalloc+0xa1/0xd0 mm/kasan/common.c:522 kasan_kmalloc include/linux/kasan.h:264 [inline] kmem_cache_alloc_trace+0x1e4/0x480 mm/slab.c:3575 kmalloc include/linux/slab.h:591 [inline] kzalloc include/linux/slab.h:721 [inline] em28xx_v4l2_init drivers/media/usb/em28xx/em28xx-video.c:2542 [inline] em28xx_v4l2_init.cold+0x91/0x2d6d drivers/media/usb/em28xx/em28xx-video.c:2520 em28xx_init_extension+0x106/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1126 process_one_work+0x84c/0x13d0 kernel/workqueue.c:2276 worker_thread+0x598/0x1040 kernel/workqueue.c:2422 kthread+0x38b/0x460 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Freed by task 10368: 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:360 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0xd1/0x110 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:230 [inline] __cache_free mm/slab.c:3445 [inline] kfree+0x10a/0x2c0 mm/slab.c:3803 em28xx_v4l2_init drivers/media/usb/em28xx/em28xx-video.c:2911 [inline] em28xx_v4l2_init.cold+0x24a/0x2d6d drivers/media/usb/em28xx/em28xx-video.c:2520 em28xx_init_extension+0x106/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1126 process_one_work+0x84c/0x13d0 kernel/workqueue.c:2276 worker_thread+0x598/0x1040 kernel/workqueue.c:2422 kthread+0x38b/0x460 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 The buggy address belongs to the object at ffff88803d478000 which belongs to the cache kmalloc-16k of size 16384 The buggy address is located 2296 bytes inside of 16384-byte region [ffff88803d478000, ffff88803d47c000) The buggy address belongs to the page: page:ffffea0000f51e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3d478 head:ffffea0000f51e00 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 ffffea0000f51c08 ffff88800fc41c50 ffff88800fc40b00 raw: 0000000000000000 ffff88803d478000 0000000100000001 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 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE), pid 10368, ts 73740463893, free_ts 71658969291 prep_new_page mm/page_alloc.c:2436 [inline] get_page_from_freelist+0xa6f/0x2f50 mm/page_alloc.c:4168 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5390 __alloc_pages_node include/linux/gfp.h:570 [inline] kmem_getpages mm/slab.c:1377 [inline] cache_grow_begin+0x75/0x460 mm/slab.c:2593 cache_alloc_refill+0x27f/0x380 mm/slab.c:2965 ____cache_alloc mm/slab.c:3048 [inline] ____cache_alloc mm/slab.c:3031 [inline] __do_cache_alloc mm/slab.c:3275 [inline] slab_alloc mm/slab.c:3316 [inline] kmem_cache_alloc_trace+0x38c/0x480 mm/slab.c:3573 kmalloc include/linux/slab.h:591 [inline] kzalloc include/linux/slab.h:721 [inline] em28xx_v4l2_init drivers/media/usb/em28xx/em28xx-video.c:2542 [inline] em28xx_v4l2_init.cold+0x91/0x2d6d drivers/media/usb/em28xx/em28xx-video.c:2520 em28xx_init_extension+0x106/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1126 process_one_work+0x84c/0x13d0 kernel/workqueue.c:2276 worker_thread+0x598/0x1040 kernel/workqueue.c:2422 kthread+0x38b/0x460 kernel/kthread.c:319 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:1346 [inline] __free_pages_ok+0x4d0/0xc00 mm/page_alloc.c:1649 slab_destroy mm/slab.c:1627 [inline] drain_freelist.isra.0+0xc6/0x120 mm/slab.c:2219 cache_reap+0x1ba/0x290 mm/slab.c:4037 process_one_work+0x84c/0x13d0 kernel/workqueue.c:2276 worker_thread+0x598/0x1040 kernel/workqueue.c:2422 kthread+0x38b/0x460 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Memory state around the buggy address: ffff88803d478780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88803d478800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88803d478880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88803d478900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88803d478980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================