bisecting fixing commit since 3906fe9bb7f1a2c8667ae54e967dc8690824f4ea
building syzkaller on d50eb50a564f0774e935b4f77390e3f591b4206d
testing commit 3906fe9bb7f1a2c8667ae54e967dc8690824f4ea
compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2
kernel signature: 2f917dca446b149da9050fc35083dceaed727c8a914908d0bcdb67ea08e66b86
run #0: crashed: KASAN: use-after-free Read in dump_schedule
run #1: crashed: KASAN: use-after-free Read in dump_schedule
run #2: crashed: KASAN: use-after-free Read in dump_schedule
run #3: crashed: KASAN: use-after-free Read in dump_schedule
run #4: crashed: KASAN: use-after-free Read in dump_schedule
run #5: crashed: KASAN: use-after-free Read in dump_schedule
run #6: crashed: KASAN: use-after-free Read in dump_schedule
run #7: crashed: KASAN: use-after-free Read in dump_schedule
run #8: crashed: KASAN: use-after-free Read in dump_schedule
run #9: OK
run #10: OK
run #11: OK
run #12: OK
run #13: OK
run #14: OK
run #15: OK
run #16: OK
run #17: OK
run #18: OK
run #19: OK
reproducer seems to be flaky
testing current HEAD 8ced7ca3570333998ad2088d5a6275701970e28e
testing commit 8ced7ca3570333998ad2088d5a6275701970e28e
compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2
kernel signature: 2d4ad3ed03579c9d4ed0f5d695b1494194e167e0d2ffc656bebcc7f6a18d109e
run #0: crashed: KASAN: use-after-free Read in dump_schedule
run #1: crashed: KASAN: use-after-free Read in dump_schedule
run #2: crashed: KASAN: use-after-free Read in dump_schedule
run #3: crashed: KASAN: use-after-free Read in dump_schedule
run #4: crashed: KASAN: use-after-free Read in dump_schedule
run #5: crashed: KASAN: use-after-free Read in dump_schedule
run #6: crashed: KASAN: use-after-free Read in dump_schedule
run #7: crashed: KASAN: use-after-free Read in dump_schedule
run #8: crashed: KASAN: use-after-free Read in dump_schedule
run #9: crashed: KASAN: use-after-free Read in dump_schedule
run #10: OK
run #11: OK
run #12: OK
run #13: OK
run #14: OK
run #15: OK
run #16: OK
run #17: OK
run #18: OK
run #19: OK
Reproducer flagged being flaky
revisions tested: 2, total time: 37m33.21187774s (build: 13m25.374135073s, test: 23m32.877855725s)
the crash still happens on HEAD
commit msg: Merge tag 'block-5.16-2021-11-25' of git://git.kernel.dk/linux-block
crash: KASAN: use-after-free Read in dump_schedule
==================================================================
BUG: KASAN: use-after-free in dump_schedule+0x6d2/0x750 net/sched/sch_taprio.c:1848
Read of size 8 at addr ffff888072928c40 by task syz-executor.5/32756

CPU: 0 PID: 32756 Comm: syz-executor.5 Not tainted 5.16.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __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/0x320 mm/kasan/report.c:247
 __kasan_report mm/kasan/report.c:433 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:450
 dump_schedule+0x6d2/0x750 net/sched/sch_taprio.c:1848
 taprio_dump+0x431/0xbd0 net/sched/sch_taprio.c:1917
 tc_fill_qdisc+0x570/0xfa0 net/sched/sch_api.c:924
 qdisc_notify.isra.0+0x229/0x2a0 net/sched/sch_api.c:990
 tc_modify_qdisc+0xc4a/0x1630 net/sched/sch_api.c:1633
 rtnetlink_rcv_msg+0x31d/0x8d0 net/core/rtnetlink.c:5571
 netlink_rcv_skb+0x118/0x370 net/netlink/af_netlink.c:2491
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x42e/0x700 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x706/0xbf0 net/netlink/af_netlink.c:1916
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xab/0xe0 net/socket.c:724
 sock_no_sendpage+0xea/0x130 net/core/sock.c:3080
 kernel_sendpage.part.0+0x121/0x250 net/socket.c:3504
 kernel_sendpage net/socket.c:3501 [inline]
 sock_sendpage+0xc7/0x1a0 net/socket.c:1003
 pipe_to_sendpage+0x245/0x410 fs/splice.c:364
 splice_from_pipe_feed fs/splice.c:418 [inline]
 __splice_from_pipe+0x362/0x810 fs/splice.c:562
 splice_from_pipe fs/splice.c:597 [inline]
 generic_splice_sendpage+0xba/0x120 fs/splice.c:746
 do_splice_from fs/splice.c:767 [inline]
 do_splice+0x9ef/0x1b30 fs/splice.c:1079
 __do_splice+0xf4/0x1b0 fs/splice.c:1144
 __do_sys_splice fs/splice.c:1350 [inline]
 __se_sys_splice fs/splice.c:1332 [inline]
 __x64_sys_splice+0x14a/0x200 fs/splice.c:1332
 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: 0033:0x7f3a7b24ba39
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3a7a9c1188 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f3a7b34ef60 RCX: 00007f3a7b24ba39
RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f3a7b2a5e8f R08: 0000000000010976 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3a7b882b2f R14: 00007f3a7a9c1300 R15: 0000000000022000
 </TASK>

Allocated by task 32725:
 kasan_save_stack+0x1e/0x50 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+0xa9/0xd0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:590 [inline]
 kzalloc include/linux/slab.h:724 [inline]
 taprio_change+0x51b/0x3a80 net/sched/sch_taprio.c:1484
 qdisc_change net/sched/sch_api.c:1329 [inline]
 tc_modify_qdisc+0xafa/0x1630 net/sched/sch_api.c:1631
 rtnetlink_rcv_msg+0x31d/0x8d0 net/core/rtnetlink.c:5571
 netlink_rcv_skb+0x118/0x370 net/netlink/af_netlink.c:2491
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x42e/0x700 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x706/0xbf0 net/netlink/af_netlink.c:1916
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xab/0xe0 net/socket.c:724
 sock_no_sendpage+0xea/0x130 net/core/sock.c:3080
 kernel_sendpage.part.0+0x121/0x250 net/socket.c:3504
 kernel_sendpage net/socket.c:3501 [inline]
 sock_sendpage+0xc7/0x1a0 net/socket.c:1003
 pipe_to_sendpage+0x245/0x410 fs/splice.c:364
 splice_from_pipe_feed fs/splice.c:418 [inline]
 __splice_from_pipe+0x362/0x810 fs/splice.c:562
 splice_from_pipe fs/splice.c:597 [inline]
 generic_splice_sendpage+0xba/0x120 fs/splice.c:746
 do_splice_from fs/splice.c:767 [inline]
 do_splice+0x9ef/0x1b30 fs/splice.c:1079
 __do_splice+0xf4/0x1b0 fs/splice.c:1144
 __do_sys_splice fs/splice.c:1350 [inline]
 __se_sys_splice fs/splice.c:1332 [inline]
 __x64_sys_splice+0x14a/0x200 fs/splice.c:1332
 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

Freed by task 7132:
 kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38
 kasan_set_track+0x21/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0xff/0x130 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:1723 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1749
 slab_free mm/slub.c:3513 [inline]
 kfree+0xf6/0x560 mm/slub.c:4561
 rcu_do_batch kernel/rcu/tree.c:2506 [inline]
 rcu_core+0x7ab/0x1470 kernel/rcu/tree.c:2741
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558

Last potentially related work creation:
 kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xf5/0x120 mm/kasan/generic.c:348
 __call_rcu kernel/rcu/tree.c:2985 [inline]
 call_rcu+0xb1/0x740 kernel/rcu/tree.c:3065
 taprio_change+0x259a/0x3a80 net/sched/sch_taprio.c:1604
 qdisc_change net/sched/sch_api.c:1329 [inline]
 tc_modify_qdisc+0xafa/0x1630 net/sched/sch_api.c:1631
 rtnetlink_rcv_msg+0x31d/0x8d0 net/core/rtnetlink.c:5571
 netlink_rcv_skb+0x118/0x370 net/netlink/af_netlink.c:2491
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x42e/0x700 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x706/0xbf0 net/netlink/af_netlink.c:1916
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xab/0xe0 net/socket.c:724
 sock_no_sendpage+0xea/0x130 net/core/sock.c:3080
 kernel_sendpage.part.0+0x121/0x250 net/socket.c:3504
 kernel_sendpage net/socket.c:3501 [inline]
 sock_sendpage+0xc7/0x1a0 net/socket.c:1003
 pipe_to_sendpage+0x245/0x410 fs/splice.c:364
 splice_from_pipe_feed fs/splice.c:418 [inline]
 __splice_from_pipe+0x362/0x810 fs/splice.c:562
 splice_from_pipe fs/splice.c:597 [inline]
 generic_splice_sendpage+0xba/0x120 fs/splice.c:746
 do_splice_from fs/splice.c:767 [inline]
 do_splice+0x9ef/0x1b30 fs/splice.c:1079
 __do_splice+0xf4/0x1b0 fs/splice.c:1144
 __do_sys_splice fs/splice.c:1350 [inline]
 __se_sys_splice fs/splice.c:1332 [inline]
 __x64_sys_splice+0x14a/0x200 fs/splice.c:1332
 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

Second to last potentially related work creation:
 kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xf5/0x120 mm/kasan/generic.c:348
 __call_rcu kernel/rcu/tree.c:2985 [inline]
 call_rcu+0xb1/0x740 kernel/rcu/tree.c:3065
 taprio_change+0x259a/0x3a80 net/sched/sch_taprio.c:1604
 qdisc_change net/sched/sch_api.c:1329 [inline]
 tc_modify_qdisc+0xafa/0x1630 net/sched/sch_api.c:1631
 rtnetlink_rcv_msg+0x31d/0x8d0 net/core/rtnetlink.c:5571
 netlink_rcv_skb+0x118/0x370 net/netlink/af_netlink.c:2491
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x42e/0x700 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x706/0xbf0 net/netlink/af_netlink.c:1916
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xab/0xe0 net/socket.c:724
 sock_no_sendpage+0xea/0x130 net/core/sock.c:3080
 kernel_sendpage.part.0+0x121/0x250 net/socket.c:3504
 kernel_sendpage net/socket.c:3501 [inline]
 sock_sendpage+0xc7/0x1a0 net/socket.c:1003
 pipe_to_sendpage+0x245/0x410 fs/splice.c:364
 splice_from_pipe_feed fs/splice.c:418 [inline]
 __splice_from_pipe+0x362/0x810 fs/splice.c:562
 splice_from_pipe fs/splice.c:597 [inline]
 generic_splice_sendpage+0xba/0x120 fs/splice.c:746
 do_splice_from fs/splice.c:767 [inline]
 do_splice+0x9ef/0x1b30 fs/splice.c:1079
 __do_splice+0xf4/0x1b0 fs/splice.c:1144
 __do_sys_splice fs/splice.c:1350 [inline]
 __se_sys_splice fs/splice.c:1332 [inline]
 __x64_sys_splice+0x14a/0x200 fs/splice.c:1332
 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

The buggy address belongs to the object at ffff888072928c00
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 64 bytes inside of
 96-byte region [ffff888072928c00, ffff888072928c60)
The buggy address belongs to the page:
page:ffffea0001ca4a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x72928
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0000731dc0 dead000000000003 ffff88800fc41780
raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY), pid 2997, ts 65996221517, free_ts 65919774631
 prep_new_page mm/page_alloc.c:2418 [inline]
 get_page_from_freelist+0xa6f/0x2f10 mm/page_alloc.c:4149
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5369
 alloc_slab_page mm/slub.c:1793 [inline]
 allocate_slab mm/slub.c:1930 [inline]
 new_slab+0x32d/0x4a0 mm/slub.c:1993
 ___slab_alloc+0x91a/0xfd0 mm/slub.c:3022
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3109
 slab_alloc_node mm/slub.c:3200 [inline]
 slab_alloc mm/slub.c:3242 [inline]
 __kmalloc+0x2fb/0x340 mm/slub.c:4419
 kmalloc include/linux/slab.h:595 [inline]
 kzalloc include/linux/slab.h:724 [inline]
 tomoyo_encode2.part.0+0x92/0x310 security/tomoyo/realpath.c:45
 tomoyo_realpath_from_path+0x140/0x6a0 security/tomoyo/realpath.c:288
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x1fb/0x350 security/tomoyo/file.c:822
 security_inode_getattr+0xab/0x100 security/security.c:1334
 vfs_getattr fs/stat.c:157 [inline]
 vfs_fstat+0x2b/0x80 fs/stat.c:182
 __do_sys_newfstat+0x72/0xd0 fs/stat.c:422
 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
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1338 [inline]
 free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1389
 free_unref_page_prepare mm/page_alloc.c:3309 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3388
 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+0xa2/0xc0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:259 [inline]
 slab_post_alloc_hook mm/slab.h:519 [inline]
 slab_alloc_node mm/slub.c:3234 [inline]
 slab_alloc mm/slub.c:3242 [inline]
 kmem_cache_alloc_trace+0x1e9/0x2c0 mm/slub.c:3259
 kmalloc include/linux/slab.h:590 [inline]
 kzalloc include/linux/slab.h:724 [inline]
 nsim_fib6_rt_create drivers/net/netdevsim/fib.c:544 [inline]
 nsim_fib6_rt_insert drivers/net/netdevsim/fib.c:749 [inline]
 nsim_fib6_event drivers/net/netdevsim/fib.c:853 [inline]
 nsim_fib_event drivers/net/netdevsim/fib.c:886 [inline]
 nsim_fib_event_work+0x1003/0x20e0 drivers/net/netdevsim/fib.c:1477
 process_one_work+0x87f/0x1450 kernel/workqueue.c:2298
 process_scheduled_works kernel/workqueue.c:2361 [inline]
 worker_thread+0x74b/0x1040 kernel/workqueue.c:2447
 kthread+0x3ab/0x480 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:
 ffff888072928b00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888072928b80: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
>ffff888072928c00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                           ^
 ffff888072928c80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888072928d00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
==================================================================