bisecting fixing commit since 414510bc00a5fc954d8340c170083f518d09aa55 building syzkaller on a60cb4cd840ce786236a00480e8bb1025e0c5fef testing commit 414510bc00a5fc954d8340c170083f518d09aa55 with gcc (GCC) 8.1.0 kernel signature: a7d61011c46bc3ef7f99a5a9e268b300eda65c5e all runs: crashed: INFO: task hung in sdr_cap_stop_streaming testing current HEAD e1f7d50ae3a3ec342e87a9b1ce6787bfb8b3c08b testing commit e1f7d50ae3a3ec342e87a9b1ce6787bfb8b3c08b with gcc (GCC) 8.1.0 kernel signature: 98d71b0f04563a9755cee82067f87275c2367c82 all runs: crashed: KASAN: use-after-free Read in __vb2_perform_fileio revisions tested: 2, total time: 33m53.138885483s (build: 15m40.16074861s, test: 17m11.073619212s) the crash still happens on HEAD commit msg: Linux 4.14.160 crash: KASAN: use-after-free Read in __vb2_perform_fileio team0 (unregistering): Port device team_slave_1 removed team0 (unregistering): Port device team_slave_0 removed bond0 (unregistering): Releasing backup interface bond_slave_1 bond0 (unregistering): Releasing backup interface bond_slave_0 ================================================================== BUG: KASAN: use-after-free in __vb2_perform_fileio+0x10fd/0x12b0 drivers/media/v4l2-core/videobuf2-core.c:2379 Read of size 4 at addr ffff8880a0edd0dc by task syz-executor306/13991 CPU: 0 PID: 13991 Comm: syz-executor306 Not tainted 4.14.160-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xf7/0x13b lib/dump_stack.c:58 print_address_description.cold.7+0x9/0x1c9 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report.cold.8+0x11a/0x2d3 mm/kasan/report.c:409 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 __vb2_perform_fileio+0x10fd/0x12b0 drivers/media/v4l2-core/videobuf2-core.c:2379 vb2_read+0xf/0x20 drivers/media/v4l2-core/videobuf2-core.c:2490 vb2_fop_read+0x1b6/0x390 drivers/media/v4l2-core/videobuf2-v4l2.c:895 v4l2_read+0x133/0x240 drivers/media/v4l2-core/v4l2-dev.c:309 __vfs_read+0xdb/0x840 fs/read_write.c:411 kobject: 'rx-0' (ffff88809f44bb50): kobject_cleanup, parent ffff8880a0710d48 vfs_read+0xf5/0x300 fs/read_write.c:447 SYSC_read fs/read_write.c:574 [inline] SyS_read+0x100/0x250 fs/read_write.c:567 kobject: 'rx-0' (ffff88809f44bb50): auto cleanup 'remove' event kobject: 'rx-0' (ffff88809f44bb50): kobject_uevent_env do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x444f19 RSP: 002b:00007ffdd32cc218 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000444f19 RDX: 000000000000001e RSI: 0000000020000300 RDI: 0000000000000003 RBP: 0000000000074a6a R08: 0000000000000004 R09: 00000000004002e0 R10: 000000000000000f R11: 0000000000000246 R12: 00000000004020b0 R13: 0000000000402140 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 13991: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:551 kmem_cache_alloc_trace+0x152/0x7a0 mm/slab.c:3618 kmalloc include/linux/slab.h:488 [inline] kzalloc include/linux/slab.h:661 [inline] __vb2_init_fileio+0x160/0xaf0 drivers/media/v4l2-core/videobuf2-core.c:2224 __vb2_perform_fileio+0xa9f/0x12b0 drivers/media/v4l2-core/videobuf2-core.c:2358 vb2_read+0xf/0x20 drivers/media/v4l2-core/videobuf2-core.c:2490 kobject: 'rx-0' (ffff88809f44bb50): kobject_uevent_env: uevent_suppress caused the event to drop! vb2_fop_read+0x1b6/0x390 drivers/media/v4l2-core/videobuf2-v4l2.c:895 v4l2_read+0x133/0x240 drivers/media/v4l2-core/v4l2-dev.c:309 __vfs_read+0xdb/0x840 fs/read_write.c:411 vfs_read+0xf5/0x300 fs/read_write.c:447 SYSC_read fs/read_write.c:574 [inline] SyS_read+0x100/0x250 fs/read_write.c:567 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 13992: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcc/0x270 mm/slab.c:3815 __vb2_cleanup_fileio+0xee/0x140 drivers/media/v4l2-core/videobuf2-core.c:2317 vb2_core_queue_release+0xf/0x70 drivers/media/v4l2-core/videobuf2-core.c:2040 vb2_queue_release drivers/media/v4l2-core/videobuf2-v4l2.c:669 [inline] _vb2_fop_release+0x1ac/0x280 drivers/media/v4l2-core/videobuf2-v4l2.c:840 vb2_fop_release+0x66/0xd0 drivers/media/v4l2-core/videobuf2-v4l2.c:854 vivid_fop_release+0x15f/0x3a0 drivers/media/platform/vivid/vivid-core.c:486 v4l2_release+0xeb/0x1a0 drivers/media/v4l2-core/v4l2-dev.c:446 __fput+0x232/0x750 fs/file_table.c:210 kobject: 'rx-0' (ffff88809f44bb50): auto cleanup kobject_del ____fput+0x9/0x10 fs/file_table.c:244 task_work_run+0xe5/0x170 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x8fb/0x2e20 kernel/exit.c:854 do_group_exit+0xf4/0x2f0 kernel/exit.c:951 SYSC_exit_group kernel/exit.c:962 [inline] SyS_exit_group+0x18/0x20 kernel/exit.c:960 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 The buggy address belongs to the object at ffff8880a0edcdc0 which belongs to the cache kmalloc-1024 of size 1024 The buggy address is located 796 bytes inside of 1024-byte region [ffff8880a0edcdc0, ffff8880a0edd1c0) The buggy address belongs to the page: kobject: 'rx-0' (ffff88809f44bb50): calling ktype release page:ffffea000283b700 count:1 mapcount:0 mapping:ffff8880a0edc040 index:0x0 compound_mapcount: 0 flags: 0x1fffc0000008100(slab|head) raw: 01fffc0000008100 ffff8880a0edc040 0000000000000000 0000000100000007 raw: ffffea0002921ca0 ffffea000281a420 ffff8880aa800ac0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a0edcf80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a0edd000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880a0edd080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a0edd100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb kobject: 'rx-0': free name ffff8880a0edd180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc kobject: 'tx-0' (ffff8880a695f798): kobject_cleanup, parent ffff8880a0710d48 ================================================================== kobject: 'tx-0' (ffff8880a695f798): auto cleanup 'remove' event