[syzbot] [kernel?] possible deadlock in stack_depot

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* [syzbot] [kernel?] possible deadlock in stack_depot_put
@ 2023-11-25 21:07 syzbot
  2023-12-03 13:17 ` [syzbot] " syzbot
       [not found] ` <20231205113107.1324-1-hdanton@sina.com>
  0 siblings, 2 replies; 8+ messages in thread
From: syzbot @ 2023-11-25 21:07 UTC (permalink / raw)
  To: frederic, linux-kernel, mingo, syzkaller-bugs, tglx

Hello,

syzbot found the following issue on:

HEAD commit:    8c9660f65153 Add linux-next specific files for 20231124
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15c1a4d8e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ca1e8655505e280
dashboard link: https://syzkaller.appspot.com/bug?extid=186b55175d8360728234
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/345ed4af3a0d/disk-8c9660f6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/191053c69d57/vmlinux-8c9660f6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/aac7ee5e55e0/bzImage-8c9660f6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+186b55175d8360728234@syzkaller.appspotmail.com

------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
6.7.0-rc2-next-20231124-syzkaller #0 Not tainted
------------------------------------------------------
jbd2/sda1-8/4474 is trying to acquire lock:
ffffffff8cf9a9b8 ((console_sem).lock){-...}-{2:2}, at: down_trylock+0x12/0x70 kernel/locking/semaphore.c:139

but task is already holding lock:
ffffffff8da73f98 (pool_rwlock){----}-{2:2}, at: stack_depot_put lib/stackdepot.c:621 [inline]
ffffffff8da73f98 (pool_rwlock){----}-{2:2}, at: stack_depot_put+0x24/0x110 lib/stackdepot.c:613

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (pool_rwlock){----}-{2:2}:
       __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
       _raw_read_lock_irqsave+0x46/0x90 kernel/locking/spinlock.c:236
       stack_depot_save_flags+0x169/0x740 lib/stackdepot.c:508
       kasan_save_stack+0x42/0x50 mm/kasan/common.c:47
       __kasan_record_aux_stack+0xc2/0xd0 mm/kasan/generic.c:508
       task_work_add+0x88/0x2a0 kernel/task_work.c:48
       task_tick_numa kernel/sched/fair.c:3512 [inline]
       task_tick_fair+0x5a5/0xc30 kernel/sched/fair.c:12599
       scheduler_tick+0x210/0x650 kernel/sched/core.c:5674
       update_process_times+0x19e/0x220 kernel/time/timer.c:2076
       tick_sched_handle+0x8e/0x170 kernel/time/tick-sched.c:255
       tick_nohz_highres_handler+0xe9/0x110 kernel/time/tick-sched.c:1516
       __run_hrtimer kernel/time/hrtimer.c:1688 [inline]
       __hrtimer_run_queues+0x654/0xc20 kernel/time/hrtimer.c:1752
       hrtimer_interrupt+0x31b/0x800 kernel/time/hrtimer.c:1814
       local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1065 [inline]
       __sysvec_apic_timer_interrupt+0x10c/0x410 arch/x86/kernel/apic/apic.c:1082
       sysvec_apic_timer_interrupt+0x90/0xb0 arch/x86/kernel/apic/apic.c:1076
       asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
       sha256_transform_rorx+0xffc/0x1120 arch/x86/crypto/sha256-avx2-asm.S:655
       lib_sha256_base_do_update.isra.0+0x12d/0x150 include/crypto/sha256_base.h:63
       sha256_base_do_update include/crypto/sha256_base.h:81 [inline]
       _sha256_update arch/x86/crypto/sha256_ssse3_glue.c:74 [inline]
       _sha256_update+0xb6/0xe0 arch/x86/crypto/sha256_ssse3_glue.c:58
       ima_calc_file_hash_tfm+0x2fe/0x3d0 security/integrity/ima/ima_crypto.c:496
       ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
       ima_calc_file_hash+0x1c6/0x4a0 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x85e/0xa20 security/integrity/ima/ima_api.c:290
       process_measurement+0xe92/0x2260 security/integrity/ima/ima_main.c:359
       ima_file_mmap+0x1ad/0x1d0 security/integrity/ima/ima_main.c:449
       security_mmap_file+0x186/0x1d0 security/security.c:2788
       vm_mmap_pgoff+0xdb/0x3c0 mm/util.c:552
       vm_mmap+0x8e/0xc0 mm/util.c:575
       elf_map fs/binfmt_elf.c:385 [inline]
       elf_load+0x196/0x870 fs/binfmt_elf.c:408
       load_elf_interp fs/binfmt_elf.c:675 [inline]
       load_elf_binary+0x3436/0x4e10 fs/binfmt_elf.c:1200
       search_binary_handler fs/exec.c:1736 [inline]
       exec_binprm fs/exec.c:1778 [inline]
       bprm_execve fs/exec.c:1853 [inline]
       bprm_execve+0x7ef/0x1a80 fs/exec.c:1809
       kernel_execve+0x3d7/0x4e0 fs/exec.c:2021
       try_to_run_init_process init/main.c:1364 [inline]
       kernel_init+0x137/0x2a0 init/main.c:1497
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

-> #2 (&rq->__lock){-.-.}-{2:2}:
       _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:558
       raw_spin_rq_lock kernel/sched/sched.h:1374 [inline]
       rq_lock kernel/sched/sched.h:1688 [inline]
       task_fork_fair+0x70/0x240 kernel/sched/fair.c:12619
       sched_cgroup_fork+0x3cf/0x510 kernel/sched/core.c:4835
       copy_process+0x6a38/0x9770 kernel/fork.c:2601
       kernel_clone+0xfd/0x940 kernel/fork.c:2899
       user_mode_thread+0xb4/0xf0 kernel/fork.c:2977
       rest_init+0x27/0x2b0 init/main.c:695
       arch_call_rest_init+0x13/0x30 init/main.c:827
       start_kernel+0x39e/0x480 init/main.c:1072
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:555
       x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:536
       secondary_startup_64_no_verify+0x166/0x16b

-> #1 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:522 [inline]
       try_to_wake_up+0x9a/0x13d0 kernel/sched/core.c:4252
       up+0x79/0xb0 kernel/locking/semaphore.c:191
       __up_console_sem kernel/printk/printk.c:340 [inline]
       __console_unlock kernel/printk/printk.c:2706 [inline]
       console_unlock+0x1cf/0x260 kernel/printk/printk.c:3038
       vprintk_emit+0x17f/0x5f0 kernel/printk/printk.c:2303
       dev_vprintk_emit drivers/base/core.c:4850 [inline]
       dev_printk_emit+0xfb/0x140 drivers/base/core.c:4861
       __dev_printk+0xf5/0x270 drivers/base/core.c:4873
       _dev_printk+0xde/0x120 drivers/base/core.c:4890
       sdev_prefix_printk+0x1a2/0x230 drivers/scsi/scsi_logging.c:78
       ioctl_internal_command.constprop.0+0x57e/0x5f0 drivers/scsi/scsi_ioctl.c:93
       scsi_send_start_stop drivers/scsi/scsi_ioctl.c:241 [inline]
       scsi_ioctl+0x46b/0x1840 drivers/scsi/scsi_ioctl.c:907
       sg_ioctl+0xb7b/0x2760 drivers/scsi/sg.c:1163
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
       entry_SYSCALL_64_after_hwframe+0x62/0x6a

-> #0 ((console_sem).lock){-...}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3868 [inline]
       __lock_acquire+0x2466/0x3b10 kernel/locking/lockdep.c:5136
       lock_acquire kernel/locking/lockdep.c:5753 [inline]
       lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
       down_trylock+0x12/0x70 kernel/locking/semaphore.c:139
       __down_trylock_console_sem+0x40/0x140 kernel/printk/printk.c:323
       console_trylock+0x73/0x130 kernel/printk/printk.c:2659
       console_trylock_spinning kernel/printk/printk.c:1923 [inline]
       vprintk_emit+0x162/0x5f0 kernel/printk/printk.c:2302
       vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45
       _printk+0xc8/0x100 kernel/printk/printk.c:2328
       __warn_printk+0x158/0x350 kernel/panic.c:721
       refcount_warn_saturate+0x149/0x210 lib/refcount.c:28
       __refcount_sub_and_test include/linux/refcount.h:283 [inline]
       __refcount_dec_and_test include/linux/refcount.h:315 [inline]
       refcount_dec_and_test include/linux/refcount.h:333 [inline]
       stack_depot_put lib/stackdepot.c:627 [inline]
       stack_depot_put+0xe4/0x110 lib/stackdepot.c:613
       __kasan_record_aux_stack+0xb3/0xd0 mm/kasan/generic.c:506
       insert_work+0x38/0x230 kernel/workqueue.c:1653
       __queue_work+0x633/0x11d0 kernel/workqueue.c:1802
       __queue_delayed_work+0x1bf/0x270 kernel/workqueue.c:1953
       mod_delayed_work_on+0xcc/0x1a0 kernel/workqueue.c:2027
       kblockd_mod_delayed_work_on+0x29/0x40 block/blk-core.c:1038
       blk_kick_flush block/blk-flush.c:348 [inline]
       blk_flush_complete_seq+0xa66/0x10c0 block/blk-flush.c:213
       blk_insert_flush+0x349/0x6d0 block/blk-flush.c:456
       blk_mq_submit_bio+0x16cd/0x2150 block/blk-mq.c:2992
       __submit_bio+0xfd/0x310 block/blk-core.c:599
       __submit_bio_noacct_mq block/blk-core.c:678 [inline]
       submit_bio_noacct_nocheck+0x852/0xbb0 block/blk-core.c:707
       submit_bio_noacct+0x87b/0x1b90 block/blk-core.c:801
       journal_submit_commit_record+0x73b/0xab0 fs/jbd2/commit.c:156
       jbd2_journal_commit_transaction+0x39fd/0x63c0 fs/jbd2/commit.c:880
       kjournald2+0x1f8/0x8f0 fs/jbd2/journal.c:201
       kthread+0x2c1/0x3a0 kernel/kthread.c:389
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

other info that might help us debug this:

Chain exists of:
  (console_sem).lock --> &rq->__lock --> pool_rwlock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(pool_rwlock);
                               lock(&rq->__lock);
                               lock(pool_rwlock);
  lock((console_sem).lock);

 *** DEADLOCK ***

4 locks held by jbd2/sda1-8/4474:
 #0: ffff88801e366218 (&fq->mq_flush_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:376 [inline]
 #0: ffff88801e366218 (&fq->mq_flush_lock){..-.}-{2:2}, at: blk_insert_flush+0x337/0x6d0 block/blk-flush.c:455
 #1: ffffffff8cfacf60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline]
 #1: ffffffff8cfacf60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]
 #1: ffffffff8cfacf60 (rcu_read_lock){....}-{1:2}, at: __queue_work+0xf2/0x11d0 kernel/workqueue.c:1730
 #2: ffff8880b993c2f8 (&pool->lock){-.-.}-{2:2}, at: __queue_work+0x39e/0x11d0 kernel/workqueue.c:1766
 #3: ffffffff8da73f98 (pool_rwlock){----}-{2:2}, at: stack_depot_put lib/stackdepot.c:621 [inline]
 #3: ffffffff8da73f98 (pool_rwlock){----}-{2:2}, at: stack_depot_put+0x24/0x110 lib/stackdepot.c:613

stack backtrace:
CPU: 1 PID: 4474 Comm: jbd2/sda1-8 Not tainted 6.7.0-rc2-next-20231124-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x316/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3868 [inline]
 __lock_acquire+0x2466/0x3b10 kernel/locking/lockdep.c:5136
 lock_acquire kernel/locking/lockdep.c:5753 [inline]
 lock_acquire+0x1b1/0x530 kernel/locking/lockdep.c:5718
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162
 down_trylock+0x12/0x70 kernel/locking/semaphore.c:139
 __down_trylock_console_sem+0x40/0x140 kernel/printk/printk.c:323
 console_trylock+0x73/0x130 kernel/printk/printk.c:2659
 console_trylock_spinning kernel/printk/printk.c:1923 [inline]
 vprintk_emit+0x162/0x5f0 kernel/printk/printk.c:2302
 vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45
 _printk+0xc8/0x100 kernel/printk/printk.c:2328
 __warn_printk+0x158/0x350 kernel/panic.c:721
 refcount_warn_saturate+0x149/0x210 lib/refcount.c:28
 __refcount_sub_and_test include/linux/refcount.h:283 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 stack_depot_put lib/stackdepot.c:627 [inline]
 stack_depot_put+0xe4/0x110 lib/stackdepot.c:613
 __kasan_record_aux_stack+0xb3/0xd0 mm/kasan/generic.c:506
 insert_work+0x38/0x230 kernel/workqueue.c:1653
 __queue_work+0x633/0x11d0 kernel/workqueue.c:1802
 __queue_delayed_work+0x1bf/0x270 kernel/workqueue.c:1953
 mod_delayed_work_on+0xcc/0x1a0 kernel/workqueue.c:2027
 kblockd_mod_delayed_work_on+0x29/0x40 block/blk-core.c:1038
 blk_kick_flush block/blk-flush.c:348 [inline]
 blk_flush_complete_seq+0xa66/0x10c0 block/blk-flush.c:213
 blk_insert_flush+0x349/0x6d0 block/blk-flush.c:456
 blk_mq_submit_bio+0x16cd/0x2150 block/blk-mq.c:2992
 __submit_bio+0xfd/0x310 block/blk-core.c:599
 __submit_bio_noacct_mq block/blk-core.c:678 [inline]
 submit_bio_noacct_nocheck+0x852/0xbb0 block/blk-core.c:707
 submit_bio_noacct+0x87b/0x1b90 block/blk-core.c:801
 journal_submit_commit_record+0x73b/0xab0 fs/jbd2/commit.c:156
 jbd2_journal_commit_transaction+0x39fd/0x63c0 fs/jbd2/commit.c:880
 kjournald2+0x1f8/0x8f0 fs/jbd2/journal.c:201
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
 </TASK>
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 4474 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 1 PID: 4474 Comm: jbd2/sda1-8 Not tainted 6.7.0-rc2-next-20231124-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 78 4b 24 fd 84 db 0f 85 66 ff ff ff e8 3b 50 24 fd c6 05 7e 9b 9f 0a 01 90 48 c7 c7 e0 c1 2e 8b e8 57 42 ea fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 18 50 24 fd 0f b6 1d 59 9b 9f 0a 31
RSP: 0018:ffffc9000e3df300 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff814e05d9
RDX: ffff88801bc89dc0 RSI: ffffffff814e05e6 RDI: 0000000000000001
RBP: ffff88806d1c243c R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff888017e80780
R13: ffff888018a92400 R14: ffff888018a9245c R15: ffff8880b993c340
FS:  0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020064000 CR3: 000000007cc12000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_sub_and_test include/linux/refcount.h:283 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 stack_depot_put lib/stackdepot.c:627 [inline]
 stack_depot_put+0xe4/0x110 lib/stackdepot.c:613
 __kasan_record_aux_stack+0xb3/0xd0 mm/kasan/generic.c:506
 insert_work+0x38/0x230 kernel/workqueue.c:1653
 __queue_work+0x633/0x11d0 kernel/workqueue.c:1802
 __queue_delayed_work+0x1bf/0x270 kernel/workqueue.c:1953
 mod_delayed_work_on+0xcc/0x1a0 kernel/workqueue.c:2027
 kblockd_mod_delayed_work_on+0x29/0x40 block/blk-core.c:1038
 blk_kick_flush block/blk-flush.c:348 [inline]
 blk_flush_complete_seq+0xa66/0x10c0 block/blk-flush.c:213
 blk_insert_flush+0x349/0x6d0 block/blk-flush.c:456
 blk_mq_submit_bio+0x16cd/0x2150 block/blk-mq.c:2992
 __submit_bio+0xfd/0x310 block/blk-core.c:599
 __submit_bio_noacct_mq block/blk-core.c:678 [inline]
 submit_bio_noacct_nocheck+0x852/0xbb0 block/blk-core.c:707
 submit_bio_noacct+0x87b/0x1b90 block/blk-core.c:801
 journal_submit_commit_record+0x73b/0xab0 fs/jbd2/commit.c:156
 jbd2_journal_commit_transaction+0x39fd/0x63c0 fs/jbd2/commit.c:880
 kjournald2+0x1f8/0x8f0 fs/jbd2/journal.c:201
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
 </TASK>


---
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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [syzbot] Re: [syzbot] [kernel?] possible deadlock in stack_depot_put
  2023-11-25 21:07 [syzbot] [kernel?] possible deadlock in stack_depot_put syzbot
@ 2023-12-03 13:17 ` syzbot
       [not found] ` <20231205113107.1324-1-hdanton@sina.com>
  1 sibling, 0 replies; 8+ messages in thread
From: syzbot @ 2023-12-03 13:17 UTC (permalink / raw)
  To: linux-kernel

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org.

***

Subject: Re: [syzbot] [kernel?] possible deadlock in stack_depot_put
Author: penguin-kernel@i-love.sakura.ne.jp

On 2023/11/26 6:07, syzbot wrote:
> refcount_t: underflow; use-after-free.

#syz set subsystems: kasan

By the way, shouldn't pool_rwlock section be guarded by printk_deferred_enter() ?


^ permalink raw reply	[flat|nested] 8+ messages in thread

[parent not found: <20231205113107.1324-1-hdanton@sina.com>]

* Re: [syzbot] [kernel?] possible deadlock in stack_depot_put
       [not found] ` <20231205113107.1324-1-hdanton@sina.com>
@ 2023-12-05 12:00   ` Tetsuo Handa
  2023-12-06  9:42     ` Petr Mladek
  0 siblings, 1 reply; 8+ messages in thread
From: Tetsuo Handa @ 2023-12-05 12:00 UTC (permalink / raw)
  To: Hillf Danton, syzbot
  Cc: linux-kernel, Matthew Wilcox, Petr Mladek, John Ogness,
	Waiman Long, Linus Torvalds, syzkaller-bugs

On 2023/12/05 20:31, Hillf Danton wrote:
> Unlike down_trylock(), mutex_trylock() is unable to trigger any lockdep
> warning, so why is a binary semaphore prefered over mutex?

The mutex has limitations which makes it impossible to use for console lock.

https://elixir.bootlin.com/linux/v6.7-rc4/source/kernel/locking/mutex.c#L537

By the way, this is a KASAN bug saying "refcount_t: underflow; use-after-free.".
Possibly a candidate for printk_deferred_enter() user?


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [syzbot] [kernel?] possible deadlock in stack_depot_put
  2023-12-05 12:00   ` Tetsuo Handa
@ 2023-12-06  9:42     ` Petr Mladek
       [not found]       ` <20231206112215.1381-1-hdanton@sina.com>
  0 siblings, 1 reply; 8+ messages in thread
From: Petr Mladek @ 2023-12-06  9:42 UTC (permalink / raw)
  To: Tetsuo Handa
  Cc: Hillf Danton, syzbot, linux-kernel, Matthew Wilcox, John Ogness,
	Waiman Long, Linus Torvalds, syzkaller-bugs

On Tue 2023-12-05 21:00:46, Tetsuo Handa wrote:
> On 2023/12/05 20:31, Hillf Danton wrote:
> > Unlike down_trylock(), mutex_trylock() is unable to trigger any lockdep
> > warning, so why is a binary semaphore prefered over mutex?
> 
> The mutex has limitations which makes it impossible to use for console lock.
> 
> https://elixir.bootlin.com/linux/v6.7-rc4/source/kernel/locking/mutex.c#L537

In particular, mutexes can't be acquired in an interrupt context not even
via mutex_trylock().

> By the way, this is a KASAN bug saying "refcount_t: underflow; use-after-free.".
> Possibly a candidate for printk_deferred_enter() user?

In practice, it would mean adding

	printk_deferred_enter()
	printk_deferred_exit()

around the KASAN/stackdepot code which might be called in any context
and might print a message. For example, see show_one_worker_pool().

It should be used only when really needed because it reduces the
chance to see the messages.

But honestly, I do not see a better solution. printk_deferred() is
used on many locations inside the scheduler to avoid these deadlocks
between console_sem and rq->lock.

It should be solved by the printk rework introducing per-console
locks. It might eventually allow to get rid of console_sem
completely. But it might be a long ride until all console
drivers get converted.

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 8+ messages in thread

[parent not found: <20231206112215.1381-1-hdanton@sina.com>]

* Re: [syzbot] [kernel?] possible deadlock in stack_depot_put
       [not found]       ` <20231206112215.1381-1-hdanton@sina.com>
@ 2023-12-06 11:40         ` Linus Torvalds
  0 siblings, 0 replies; 8+ messages in thread
From: Linus Torvalds @ 2023-12-06 11:40 UTC (permalink / raw)
  To: Hillf Danton
  Cc: Petr Mladek, Tetsuo Handa, syzbot, linux-kernel, Matthew Wilcox,
	John Ogness, Waiman Long, syzkaller-bugs

On Wed, 6 Dec 2023 at 20:22, Hillf Danton <hdanton@sina.com> wrote:
>
> Given the same pattern in both up() and __mutex_unlock_slowpath() where
> acquire raw spinlock to wake waiter up, it is safe to unlock mutex in
> irq context.

What? No. That spinlock is exactly why it is NOT OK to unlock a mutex
in irq context.

If somebody else is trying to get or release the mutex at the same
time an interrupt happens, you now have an immediate deadlock.

No spinlocks - raw or not - are irq safe.

The only way you make them irq-safe is by disabling interrupts
entirely across the locked region, which the mutex code very much does
not do, and does not want to do.

So no. Mutexes are not usable from interrupts.

So repeat after me: MUTEXES CANNOT BE USED IN ANY FORM IN INTERRUPT
CONTEXT. End of story.

Other locks do work. completions are designed to be done from
interrupts. And our legacy semaphores were irq-safe (for wakeups) from
day one, which is then why the spinlock in the legacy semaphore is
done with interrupts disabled, and why you can do "down_trylock()" and
"up[()" in interrupt context.

But mutexes wanted to consciously avoid that, partly *exactly* because
they didn't want to have the more expensive irq-safe spinlocks
(particularly with the debugging versions)

            Linus

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [syzbot] [kernel?] possible deadlock in stack_depot_put
@ 2023-11-27  1:29 xingwei lee
  0 siblings, 0 replies; 8+ messages in thread
From: xingwei lee @ 2023-11-27  1:29 UTC (permalink / raw)
  To: syzbot+186b55175d8360728234
  Cc: frederic, linux-kernel, mingo, syzkaller-bugs, tglx

[-- Attachment #1: Type: text/plain, Size: 4694 bytes --]

Hi, I reproduce this bug with repro.c and repro.txt and confirmed the crash.

repro.txt
r0 = socket$alg(0x26, 0x5, 0x0)
bind$alg(r0, &(0x7f0000000440)={0x26, 'skcipher\x00', 0x0, 0x0,
'ecb-cipher_null\x00'}, 0x58)
r1 = accept$alg(r0, 0x0, 0x0)
r2 = dup(r1)
open(&(0x7f0000000140)='./file1\x00', 0x10f0c2, 0x0)
r3 = dup(r1)
mount$9p_fd(0x0, &(0x7f0000000000)='./file1\x00', &(0x7f0000000040),
0x0, &(0x7f0000000a40)=ANY=[@ANYBLOB='trans=fd,rfdno=', @ANYRESHEX=r3,
@ANYBLOB=',wfdno=', @ANYRESHEX=r2])

repro.c

#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

static void sleep_ms(uint64_t ms)
{
usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts))
exit(1);
return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static bool write_file(const char* file, const char* what, ...)
{
char buf[1024];
va_list args;
va_start(args, what);
vsnprintf(buf, sizeof(buf), what, args);
va_end(args);
buf[sizeof(buf) - 1] = 0;
int len = strlen(buf);
int fd = open(file, O_WRONLY | O_CLOEXEC);
if (fd == -1)
return false;
if (write(fd, buf, len) != len) {
int err = errno;
close(fd);
errno = err;
return false;
}
close(fd);
return true;
}

static void kill_and_wait(int pid, int* status)
{
kill(-pid, SIGKILL);
kill(pid, SIGKILL);
for (int i = 0; i < 100; i++) {
if (waitpid(-1, status, WNOHANG | __WALL) == pid)
return;
usleep(1000);
}
DIR* dir = opendir("/sys/fs/fuse/connections");
if (dir) {
for (;;) {
struct dirent* ent = readdir(dir);
if (!ent)
break;
if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
continue;
char abort[300];
snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort",
ent->d_name);
int fd = open(abort, O_WRONLY);
if (fd == -1) {
continue;
}
if (write(fd, abort, 1) < 0) {
}
close(fd);
}
closedir(dir);
} else {
}
while (waitpid(-1, status, __WALL) != pid) {
}
}

static void setup_test()
{
prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
setpgrp();
write_file("/proc/self/oom_score_adj", "1000");
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
int iter = 0;
for (;; iter++) {
int pid = fork();
if (pid < 0)
exit(1);
if (pid == 0) {
setup_test();
execute_one();
exit(0);
}
int status = 0;
uint64_t start = current_time_ms();
for (;;) {
if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
break;
sleep_ms(1);
if (current_time_ms() - start < 5000)
continue;
kill_and_wait(pid, &status);
break;
}
}
}

uint64_t r[4] = {0xffffffffffffffff, 0xffffffffffffffff,
0xffffffffffffffff, 0xffffffffffffffff};

void execute_one(void)
{
intptr_t res = 0;
res = syscall(__NR_socket, /*domain=*/0x26ul, /*type=*/5ul, /*proto=*/0);
if (res != -1)
r[0] = res;
*(uint16_t*)0x20000440 = 0x26;
memcpy((void*)0x20000442, "skcipher\000\000\000\000\000\000", 14);
*(uint32_t*)0x20000450 = 0;
*(uint32_t*)0x20000454 = 0;
memcpy((void*)0x20000458,
"ecb-cipher_null\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000",
64);
syscall(__NR_bind, /*fd=*/r[0], /*addr=*/0x20000440ul, /*addrlen=*/0x58ul);
res = syscall(__NR_accept, /*fd=*/r[0], /*peer=*/0ul, /*peerlen=*/0ul);
if (res != -1)
r[1] = res;
res = syscall(__NR_dup, /*oldfd=*/r[1]);
if (res != -1)
r[2] = res;
memcpy((void*)0x20000140, "./file1\000", 8);
syscall(__NR_open, /*file=*/0x20000140ul, /*flags=*/0x10f0c2ul, /*mode=*/0ul);
res = syscall(__NR_dup, /*oldfd=*/r[1]);
if (res != -1)
r[3] = res;
memcpy((void*)0x20000000, "./file1\000", 8);
memcpy((void*)0x20000040, "9p\000", 3);
memcpy((void*)0x20000a40, "trans=fd,rfdno=", 15);
sprintf((char*)0x20000a4f, "0x%016llx", (long long)r[3]);
memcpy((void*)0x20000a61, ",wfdno=", 7);
sprintf((char*)0x20000a68, "0x%016llx", (long long)r[2]);
syscall(__NR_mount, /*src=*/0ul, /*dst=*/0x20000000ul,
/*type=*/0x20000040ul, /*flags=*/0ul, /*opts=*/0x20000a40ul);

}
int main(void)
{
syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul,
/*prot=*/0ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul,
/*prot=*/7ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul,
/*prot=*/0ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
loop();
return 0;
}

[-- Attachment #2: repro.txt --]
[-- Type: text/plain, Size: 410 bytes --]

r0 = socket$alg(0x26, 0x5, 0x0)
bind$alg(r0, &(0x7f0000000440)={0x26, 'skcipher\x00', 0x0, 0x0, 'ecb-cipher_null\x00'}, 0x58)
r1 = accept$alg(r0, 0x0, 0x0)
r2 = dup(r1)
open(&(0x7f0000000140)='./file1\x00', 0x10f0c2, 0x0)
r3 = dup(r1)
mount$9p_fd(0x0, &(0x7f0000000000)='./file1\x00', &(0x7f0000000040), 0x0, &(0x7f0000000a40)=ANY=[@ANYBLOB='trans=fd,rfdno=', @ANYRESHEX=r3, @ANYBLOB=',wfdno=', @ANYRESHEX=r2])

[-- Attachment #3: repro.c --]
[-- Type: application/octet-stream, Size: 4445 bytes --]

// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

static void sleep_ms(uint64_t ms)
{
	usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
	struct timespec ts;
	if (clock_gettime(CLOCK_MONOTONIC, &ts))
		exit(1);
	return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static bool write_file(const char* file, const char* what, ...)
{
	char buf[1024];
	va_list args;
	va_start(args, what);
	vsnprintf(buf, sizeof(buf), what, args);
	va_end(args);
	buf[sizeof(buf) - 1] = 0;
	int len = strlen(buf);
	int fd = open(file, O_WRONLY | O_CLOEXEC);
	if (fd == -1)
		return false;
	if (write(fd, buf, len) != len) {
		int err = errno;
		close(fd);
		errno = err;
		return false;
	}
	close(fd);
	return true;
}

static void kill_and_wait(int pid, int* status)
{
	kill(-pid, SIGKILL);
	kill(pid, SIGKILL);
	for (int i = 0; i < 100; i++) {
		if (waitpid(-1, status, WNOHANG | __WALL) == pid)
			return;
		usleep(1000);
	}
	DIR* dir = opendir("/sys/fs/fuse/connections");
	if (dir) {
		for (;;) {
			struct dirent* ent = readdir(dir);
			if (!ent)
				break;
			if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
				continue;
			char abort[300];
			snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort", ent->d_name);
			int fd = open(abort, O_WRONLY);
			if (fd == -1) {
				continue;
			}
			if (write(fd, abort, 1) < 0) {
			}
			close(fd);
		}
		closedir(dir);
	} else {
	}
	while (waitpid(-1, status, __WALL) != pid) {
	}
}

static void setup_test()
{
	prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
	setpgrp();
	write_file("/proc/self/oom_score_adj", "1000");
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
	int iter = 0;
	for (;; iter++) {
		int pid = fork();
		if (pid < 0)
			exit(1);
		if (pid == 0) {
			setup_test();
			execute_one();
			exit(0);
		}
		int status = 0;
		uint64_t start = current_time_ms();
		for (;;) {
			if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
				break;
			sleep_ms(1);
			if (current_time_ms() - start < 5000)
				continue;
			kill_and_wait(pid, &status);
			break;
		}
	}
}

uint64_t r[4] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff};

void execute_one(void)
{
	intptr_t res = 0;
	res = syscall(__NR_socket, /*domain=*/0x26ul, /*type=*/5ul, /*proto=*/0);
	if (res != -1)
		r[0] = res;
	*(uint16_t*)0x20000440 = 0x26;
	memcpy((void*)0x20000442, "skcipher\000\000\000\000\000\000", 14);
	*(uint32_t*)0x20000450 = 0;
	*(uint32_t*)0x20000454 = 0;
	memcpy((void*)0x20000458, "ecb-cipher_null\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000", 64);
	syscall(__NR_bind, /*fd=*/r[0], /*addr=*/0x20000440ul, /*addrlen=*/0x58ul);
	res = syscall(__NR_accept, /*fd=*/r[0], /*peer=*/0ul, /*peerlen=*/0ul);
	if (res != -1)
		r[1] = res;
	res = syscall(__NR_dup, /*oldfd=*/r[1]);
	if (res != -1)
		r[2] = res;
	memcpy((void*)0x20000140, "./file1\000", 8);
	syscall(__NR_open, /*file=*/0x20000140ul, /*flags=*/0x10f0c2ul, /*mode=*/0ul);
	res = syscall(__NR_dup, /*oldfd=*/r[1]);
	if (res != -1)
		r[3] = res;
	memcpy((void*)0x20000000, "./file1\000", 8);
	memcpy((void*)0x20000040, "9p\000", 3);
	memcpy((void*)0x20000a40, "trans=fd,rfdno=", 15);
	sprintf((char*)0x20000a4f, "0x%016llx", (long long)r[3]);
	memcpy((void*)0x20000a61, ",wfdno=", 7);
	sprintf((char*)0x20000a68, "0x%016llx", (long long)r[2]);
	syscall(__NR_mount, /*src=*/0ul, /*dst=*/0x20000000ul, /*type=*/0x20000040ul, /*flags=*/0ul, /*opts=*/0x20000a40ul);

}
int main(void)
{
	syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
	syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul, /*prot=*/7ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
	syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
	loop();
	return 0;
}

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [syzbot] [kernel?] possible deadlock in stack_depot_put
@ 2023-11-27  1:56 xingwei lee
  2023-11-27  9:03 ` Ingo Molnar
  0 siblings, 1 reply; 8+ messages in thread
From: xingwei lee @ 2023-11-27  1:56 UTC (permalink / raw)
  To: syzbot+186b55175d8360728234
  Cc: frederic, linux-kernel, mingo, syzkaller-bugs, tglx

Sorry for containing HTML subpart, I'll repeat this mail.
Hi, I reproduce this bug with repro.c and repro.txt and confirmed crash.

repro.txt
r0 = socket$alg(0x26, 0x5, 0x0)
bind$alg(r0, &(0x7f0000000440)={0x26, 'skcipher\x00', 0x0, 0x0,
'ecb-cipher_null\x00'}, 0x58)
r1 = accept$alg(r0, 0x0, 0x0)
r2 = dup(r1)
open(&(0x7f0000000140)='./file1\x00', 0x10f0c2, 0x0)
r3 = dup(r1)
mount$9p_fd(0x0, &(0x7f0000000000)='./file1\x00', &(0x7f0000000040),
0x0, &(0x7f0000000a40)=ANY=[@ANYBLOB='trans=fd,rfdno=', @ANYRESHEX=r3,
@ANYBLOB=',wfdno=', @ANYRESHEX=r2])

repro.c

#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

static void sleep_ms(uint64_t ms)
{
usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts))
exit(1);
return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static bool write_file(const char* file, const char* what, ...)
{
char buf[1024];
va_list args;
va_start(args, what);
vsnprintf(buf, sizeof(buf), what, args);
va_end(args);
buf[sizeof(buf) - 1] = 0;
int len = strlen(buf);
int fd = open(file, O_WRONLY | O_CLOEXEC);
if (fd == -1)
return false;
if (write(fd, buf, len) != len) {
int err = errno;
close(fd);
errno = err;
return false;
}
close(fd);
return true;
}

static void kill_and_wait(int pid, int* status)
{
kill(-pid, SIGKILL);
kill(pid, SIGKILL);
for (int i = 0; i < 100; i++) {
if (waitpid(-1, status, WNOHANG | __WALL) == pid)
return;
usleep(1000);
}
DIR* dir = opendir("/sys/fs/fuse/connections");
if (dir) {
for (;;) {
struct dirent* ent = readdir(dir);
if (!ent)
break;
if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
continue;
char abort[300];
snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort",
ent->d_name);
int fd = open(abort, O_WRONLY);
if (fd == -1) {
continue;
}
if (write(fd, abort, 1) < 0) {
}
close(fd);
}
closedir(dir);
} else {
}
while (waitpid(-1, status, __WALL) != pid) {
}
}

static void setup_test()
{
prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
setpgrp();
write_file("/proc/self/oom_score_adj", "1000");
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
int iter = 0;
for (;; iter++) {
int pid = fork();
if (pid < 0)
exit(1);
if (pid == 0) {
setup_test();
execute_one();
exit(0);
}
int status = 0;
uint64_t start = current_time_ms();
for (;;) {
if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
break;
sleep_ms(1);
if (current_time_ms() - start < 5000)
continue;
kill_and_wait(pid, &status);
break;
}
}
}

uint64_t r[4] = {0xffffffffffffffff, 0xffffffffffffffff,
0xffffffffffffffff, 0xffffffffffffffff};

void execute_one(void)
{
intptr_t res = 0;
res = syscall(__NR_socket, /*domain=*/0x26ul, /*type=*/5ul, /*proto=*/0);
if (res != -1)
r[0] = res;
*(uint16_t*)0x20000440 = 0x26;
memcpy((void*)0x20000442, "skcipher\000\000\000\000\000\000", 14);
*(uint32_t*)0x20000450 = 0;
*(uint32_t*)0x20000454 = 0;
memcpy((void*)0x20000458,
"ecb-cipher_null\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000",
64);
syscall(__NR_bind, /*fd=*/r[0], /*addr=*/0x20000440ul, /*addrlen=*/0x58ul);
res = syscall(__NR_accept, /*fd=*/r[0], /*peer=*/0ul, /*peerlen=*/0ul);
if (res != -1)
r[1] = res;
res = syscall(__NR_dup, /*oldfd=*/r[1]);
if (res != -1)
r[2] = res;
memcpy((void*)0x20000140, "./file1\000", 8);
syscall(__NR_open, /*file=*/0x20000140ul, /*flags=*/0x10f0c2ul, /*mode=*/0ul);
res = syscall(__NR_dup, /*oldfd=*/r[1]);
if (res != -1)
r[3] = res;
memcpy((void*)0x20000000, "./file1\000", 8);
memcpy((void*)0x20000040, "9p\000", 3);
memcpy((void*)0x20000a40, "trans=fd,rfdno=", 15);
sprintf((char*)0x20000a4f, "0x%016llx", (long long)r[3]);
memcpy((void*)0x20000a61, ",wfdno=", 7);
sprintf((char*)0x20000a68, "0x%016llx", (long long)r[2]);
syscall(__NR_mount, /*src=*/0ul, /*dst=*/0x20000000ul,
/*type=*/0x20000040ul, /*flags=*/0ul, /*opts=*/0x20000a40ul);

}
int main(void)
{
syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul,
/*prot=*/0ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul,
/*prot=*/7ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul,
/*prot=*/0ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);
loop();
return 0;
}

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [syzbot] [kernel?] possible deadlock in stack_depot_put
  2023-11-27  1:56 xingwei lee
@ 2023-11-27  9:03 ` Ingo Molnar
  0 siblings, 0 replies; 8+ messages in thread
From: Ingo Molnar @ 2023-11-27  9:03 UTC (permalink / raw)
  To: xingwei lee
  Cc: syzbot+186b55175d8360728234, frederic, linux-kernel,
	syzkaller-bugs, tglx


* xingwei lee <xrivendell7@gmail.com> wrote:

> Sorry for containing HTML subpart, I'll repeat this mail.
> Hi, I reproduce this bug with repro.c and repro.txt and confirmed crash.
> 
> repro.txt
> r0 = socket$alg(0x26, 0x5, 0x0)
> bind$alg(r0, &(0x7f0000000440)={0x26, 'skcipher\x00', 0x0, 0x0,
> 'ecb-cipher_null\x00'}, 0x58)
> r1 = accept$alg(r0, 0x0, 0x0)
> r2 = dup(r1)
> open(&(0x7f0000000140)='./file1\x00', 0x10f0c2, 0x0)
> r3 = dup(r1)
> mount$9p_fd(0x0, &(0x7f0000000000)='./file1\x00', &(0x7f0000000040),
> 0x0, &(0x7f0000000a40)=ANY=[@ANYBLOB='trans=fd,rfdno=', @ANYRESHEX=r3,
> @ANYBLOB=',wfdno=', @ANYRESHEX=r2])
> 
> repro.c
> 
> #define _GNU_SOURCE
> 
> #include <dirent.h>
> #include <endian.h>
> #include <errno.h>
> #include <fcntl.h>
> #include <signal.h>
> #include <stdarg.h>
> #include <stdbool.h>
> #include <stdint.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/prctl.h>
> #include <sys/stat.h>
> #include <sys/syscall.h>
> #include <sys/types.h>
> #include <sys/wait.h>
> #include <time.h>
> #include <unistd.h>
> 
> static void sleep_ms(uint64_t ms)
> {
> usleep(ms * 1000);
> }
> 
> static uint64_t current_time_ms(void)
> {
> struct timespec ts;
> if (clock_gettime(CLOCK_MONOTONIC, &ts))
> exit(1);
> return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
> }
> 
> static bool write_file(const char* file, const char* what, ...)
> {
> char buf[1024];
> va_list args;
> va_start(args, what);
> vsnprintf(buf, sizeof(buf), what, args);
> va_end(args);
> buf[sizeof(buf) - 1] = 0;
> int len = strlen(buf);
> int fd = open(file, O_WRONLY | O_CLOEXEC);
> if (fd == -1)
> return false;
> if (write(fd, buf, len) != len) {
> int err = errno;
> close(fd);
> errno = err;
> return false;

BTW., could you please run such autogenerated repro.c files through
"indent --linux-style"? See below, the code becomes much more readable.

Thanks,

	Ingo

============================>
#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

static void sleep_ms(uint64_t ms)
{
	usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
	struct timespec ts;

	if (clock_gettime(CLOCK_MONOTONIC, &ts))
		exit(1);
	return (uint64_t) ts.tv_sec * 1000 + (uint64_t) ts.tv_nsec / 1000000;
}

static bool write_file(const char *file, const char *what, ...)
{
	char buf[1024];
	va_list args;

	va_start(args, what);
	vsnprintf(buf, sizeof(buf), what, args);
	va_end(args);
	buf[sizeof(buf) - 1] = 0;
	int len = strlen(buf);
	int fd = open(file, O_WRONLY | O_CLOEXEC);

	if (fd == -1)
		return false;
	if (write(fd, buf, len) != len) {
		int err = errno;

		close(fd);
		errno = err;
		return false;
	}
	close(fd);
	return true;
}

static void kill_and_wait(int pid, int *status)
{
	kill(-pid, SIGKILL);
	kill(pid, SIGKILL);
	for (int i = 0; i < 100; i++) {
		if (waitpid(-1, status, WNOHANG | __WALL) == pid)
			return;
		usleep(1000);
	}
	DIR *dir = opendir("/sys/fs/fuse/connections");

	if (dir) {
		for (;;) {
			struct dirent *ent = readdir(dir);

			if (!ent)
				break;
			if (strcmp(ent->d_name, ".") == 0
			    || strcmp(ent->d_name, "..") == 0)
				continue;
			char abort[300];

			snprintf(abort, sizeof(abort),
				 "/sys/fs/fuse/connections/%s/abort",
				 ent->d_name);
			int fd = open(abort, O_WRONLY);

			if (fd == -1) {
				continue;
			}
			if (write(fd, abort, 1) < 0) {
			}
			close(fd);
		}
		closedir(dir);
	} else {
	}
	while (waitpid(-1, status, __WALL) != pid) {
	}
}

static void setup_test()
{
	prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
	setpgrp();
	write_file("/proc/self/oom_score_adj", "1000");
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
	int iter = 0;

	for (;; iter++) {
		int pid = fork();

		if (pid < 0)
			exit(1);
		if (pid == 0) {
			setup_test();
			execute_one();
			exit(0);
		}
		int status = 0;
		uint64_t start = current_time_ms();

		for (;;) {
			if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
				break;
			sleep_ms(1);
			if (current_time_ms() - start < 5000)
				continue;
			kill_and_wait(pid, &status);
			break;
		}
	}
}

uint64_t r[4] = { 0xffffffffffffffff, 0xffffffffffffffff,
	0xffffffffffffffff, 0xffffffffffffffff
};

void execute_one(void)
{
	intptr_t res = 0;

	res = syscall(__NR_socket, /*domain= */ 0x26ul, /*type= */ 5ul,
		      /*proto= */ 0);
	if (res != -1)
		r[0] = res;
	*(uint16_t *) 0x20000440 = 0x26;
	memcpy((void *)0x20000442, "skcipher\000\000\000\000\000\000", 14);
	*(uint32_t *) 0x20000450 = 0;
	*(uint32_t *) 0x20000454 = 0;
	memcpy((void *)0x20000458,
	       "ecb-cipher_null\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000",
	       64);
	syscall(__NR_bind, /*fd= */ r[0], /*addr= */ 0x20000440ul,	/*addrlen= */
		0x58ul);
	res = syscall(__NR_accept, /*fd= */ r[0], /*peer= */ 0ul,	/*peerlen= */
		      0ul);
	if (res != -1)
		r[1] = res;
	res = syscall(__NR_dup, /*oldfd= */ r[1]);
	if (res != -1)
		r[2] = res;
	memcpy((void *)0x20000140, "./file1\000", 8);
	syscall(__NR_open, /*file= */ 0x20000140ul, /*flags= */ 0x10f0c2ul,
		/*mode= */ 0ul);
	res = syscall(__NR_dup, /*oldfd= */ r[1]);
	if (res != -1)
		r[3] = res;
	memcpy((void *)0x20000000, "./file1\000", 8);
	memcpy((void *)0x20000040, "9p\000", 3);
	memcpy((void *)0x20000a40, "trans=fd,rfdno=", 15);
	sprintf((char *)0x20000a4f, "0x%016llx", (long long)r[3]);
	memcpy((void *)0x20000a61, ",wfdno=", 7);
	sprintf((char *)0x20000a68, "0x%016llx", (long long)r[2]);
	syscall(__NR_mount, /*src= */ 0ul, /*dst= */ 0x20000000ul,
		/*type= */ 0x20000040ul, /*flags= */ 0ul,	/*opts= */
		0x20000a40ul);

}

int main(void)
{
	syscall(__NR_mmap, /*addr= */ 0x1ffff000ul, /*len= */ 0x1000ul,
		/*prot= */ 0ul, /*flags= */ 0x32ul, /*fd= */ -1,	/*offset= */
		0ul);
	syscall(__NR_mmap, /*addr= */ 0x20000000ul, /*len= */ 0x1000000ul,
		/*prot= */ 7ul, /*flags= */ 0x32ul, /*fd= */ -1,	/*offset= */
		0ul);
	syscall(__NR_mmap, /*addr= */ 0x21000000ul, /*len= */ 0x1000ul,
		/*prot= */ 0ul, /*flags= */ 0x32ul, /*fd= */ -1,	/*offset= */
		0ul);
	loop();
	return 0;
}

^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2023-12-06 11:40 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-11-25 21:07 [syzbot] [kernel?] possible deadlock in stack_depot_put syzbot
2023-12-03 13:17 ` [syzbot] " syzbot
     [not found] ` <20231205113107.1324-1-hdanton@sina.com>
2023-12-05 12:00   ` Tetsuo Handa
2023-12-06  9:42     ` Petr Mladek
     [not found]       ` <20231206112215.1381-1-hdanton@sina.com>
2023-12-06 11:40         ` Linus Torvalds
  -- strict thread matches above, loose matches on Subject: below --
2023-11-27  1:29 xingwei lee
2023-11-27  1:56 xingwei lee
2023-11-27  9:03 ` Ingo Molnar

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