[syzbot] INFO: task can't die in asm_sysvec_apic_timer_interrupt (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    93717cde744f Add linux-next specific files for 20210830
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15ef5ba9300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c643ef5289990dd1
dashboard link: https://syzkaller.appspot.com/bug?extid=ac4f41effb32ce6491c0
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17bde2f5300000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15d11625300000

Bisection is inconclusive: the first bad commit could be any of:

0ee50b47532a namei: change filename_parentat() calling conventions
584d3226d665 namei: make do_mkdirat() take struct filename

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=129f0125300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ac4f41effb32ce6491c0@xxxxxxxxxxxxxxxxxxxxxxxxx

INFO: task syz-executor702:6954 can't die for more than 143 seconds.
task:syz-executor702 state:R  running task     stack:24344 pid: 6954 ppid:  6540 flags:0x00004006
Call Trace:
 context_switch kernel/sched/core.c:4955 [inline]
 __schedule+0x940/0x26f0 kernel/sched/core.c:6302
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0000:0xffffc900034bf728
RSP: 34bf748:0000000000000000 EFLAGS: 00000046 ORIG_RAX: ffffffff89400c02
==================================================================
BUG: KASAN: stack-out-of-bounds in __show_regs.cold+0x2b/0x481 arch/x86/kernel/process_64.c:81
Read of size 8 at addr ffffc900034bf6c0 by task khungtaskd/27

CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.14.0-next-20210830-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+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0xf/0x309 mm/kasan/report.c:256
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
 __show_regs.cold+0x2b/0x481 arch/x86/kernel/process_64.c:81
 show_trace_log_lvl+0x25b/0x2ba arch/x86/kernel/dumpstack.c:298
 sched_show_task kernel/sched/core.c:8560 [inline]
 sched_show_task+0x433/0x5b0 kernel/sched/core.c:8534
 check_killed_task kernel/hung_task.c:184 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:242 [inline]
 watchdog.cold+0x74/0x1de kernel/hung_task.c:339
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295


Memory state around the buggy address:
 ffffc900034bf580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900034bf600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900034bf680: 00 00 00 f1 f1 f1 f1 00 00 f3 f3 00 00 00 00 00
                                           ^
 ffffc900034bf700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900034bf780: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 f2
==================================================================


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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
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