On Tue, 7 Sep 2021 09:22:03 +0800 Hao Sun wrote:
> When using Healer to fuzz the latest Linux kernel, the following crash
> was triggered.
>
> HEAD commit: 27151f177827 Merge tag 'perf-tools-for-v5.15-2021-09-04'
> git tree: upstream
> console output:
>
https://drive.google.com/file/d/1M5oyA_IcWSDB2XpnoX8SDmKJA3JhKltz/view?usp=sharing
> kernel config:
https://drive.google.com/file/d/1ZMVJ2vNe0EiIEeWNVyrGb7hBdOG5Uj3e/view?usp=sharing
> C reproducer:
https://drive.google.com/file/d/1AtDNXl8XEBfglKXsKsAH2NuXBcrp8Zp9/view?usp=sharing
> Syzlang reproducer:
>
https://drive.google.com/file/d/1R_XD_cyMNS0Q_SGSqomRy_LIClOrd-gI/view?usp=sharing
>
> If you fix this issue, please add the following tag to the commit:
> Reported-by: Hao Sun <
sunh...@gmail.com>
Thanks for reporting it.
>
> ODEBUG: object ffffc9000073cda0 is NOT on stack ffffc90005f34000, but annotated.
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 27648 at lib/debugobjects.c:548
> debug_object_is_on_stack lib/debugobjects.c:545 [inline]
> WARNING: CPU: 2 PID: 27648 at lib/debugobjects.c:548
> __debug_object_init+0x224/0x520 lib/debugobjects.c:607
> Modules linked in:
> CPU: 2 PID: 27648 Comm: syz-executor Not tainted 5.14.0+ #13
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> RIP: 0010:debug_object_is_on_stack lib/debugobjects.c:545 [inline]
> RIP: 0010:__debug_object_init+0x224/0x520 lib/debugobjects.c:607
> Code: 84 ca fe ff ff 83 c0 01 4c 89 f6 48 c7 c7 f8 b0 3c 85 89 05 7e
> c2 56 06 65 48 8b 04 25 40 70 01 00 48 8b 50 20 e8 05 9b f5 01 <0f> 0b
> e9 9e fe ff ff 89 05 87 4d e3 03 e9 c4 fe ff ff 48 c7 c7 e0
> RSP: 0018:ffffc9000073ccf0 EFLAGS: 00010282
> RAX: 0000000000000050 RBX: ffff88810cf2f398 RCX: 0000000000000100
> RDX: 0000000000000000 RSI: ffffffff812cf85c RDI: 00000000ffffffff
> RBP: ffffffff88868538 R08: 0000000000000000 R09: 0000000000000001
> R10: ffffc9000073cc80 R11: 0000000000000005 R12: 0000000000000203
> R13: 0000000000054450 R14: ffffc9000073cda0 R15: ffff88807dd264f0
> FS: 0000000002ad0940(0000) GS:ffff88807dd00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000005061ec CR3: 0000000100da5000 CR4: 0000000000750ee0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
> Call Trace:
> <IRQ>
> __init_work+0x3f/0x50 kernel/workqueue.c:519
> synchronize_rcu_expedited+0x26a/0x460 kernel/rcu/tree_exp.h:847
Given wait_event() in synchronize_rcu_expedited(), it is no good to come
in a rcu context.
> bdi_remove_from_list mm/backing-dev.c:938 [inline]
> bdi_unregister+0x97/0x270 mm/backing-dev.c:946
> release_bdi+0x4a/0x70 mm/backing-dev.c:968
> kref_put include/linux/kref.h:65 [inline]
> bdi_put+0x47/0x70 mm/backing-dev.c:976
> bdev_free_inode+0x59/0xc0 fs/block_dev.c:819
> i_callback+0x24/0x50 fs/inode.c:224
> rcu_do_batch kernel/rcu/tree.c:2508 [inline]
> rcu_core+0x2d6/0x9f0 kernel/rcu/tree.c:2743
> __do_softirq+0xe9/0x561 kernel/softirq.c:558
> invoke_softirq kernel/softirq.c:432 [inline]
> __irq_exit_rcu kernel/softirq.c:636 [inline]
> irq_exit_rcu+0xe2/0x100 kernel/softirq.c:648
> sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1097
> </IRQ>
> asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
> RIP: 0010:__sanitizer_cov_trace_pc+0x37/0x60 kernel/kcov.c:197
> Code: 65 48 8b 14 25 40 70 01 00 81 e1 00 01 00 00 a9 00 01 ff 00 74
> 0e 85 c9 74 35 8b 82 34 15 00 00 85 c0 74 2b 8b 82 10 15 00 00 <83> f8
> 02 75 20 48 8b 8a 18 15 00 00 8b 92 14 15 00 00 48 8b 01 48
> RSP: 0018:ffffc90005f37b78 EFLAGS: 00000246
> RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000000000
> RDX: ffff888109448000 RSI: ffffffff8212a28c RDI: ffffc90005f37d30
> RBP: 0000000000000006 R08: 0000000000000d40 R09: ffff8880165fc5e0
> R10: ffffc90005f37cd0 R11: 0000000000000003 R12: 0000000000000375
> R13: ffff888107597b40 R14: ffffc90005f37d30 R15: ffff8880174b0ea0
> tomoyo_domain_quota_is_ok+0xac/0x150 security/tomoyo/util.c:1092
> tomoyo_supervisor+0x228/0x7f0 security/tomoyo/common.c:2089
> tomoyo_audit_path_log security/tomoyo/file.c:168 [inline]
> tomoyo_path_permission+0xa0/0xf0 security/tomoyo/file.c:587
> tomoyo_path_perm+0x22f/0x2d0 security/tomoyo/file.c:838
> tomoyo_path_symlink+0x43/0x70 security/tomoyo/tomoyo.c:199
> security_path_symlink+0x48/0x80 security/security.c:1164
> do_symlinkat+0x75/0x120 fs/namei.c:4274
> __do_sys_symlink fs/namei.c:4301 [inline]
> __se_sys_symlink fs/namei.c:4299 [inline]
> __x64_sys_symlink+0x3a/0x40 fs/namei.c:4299
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x46a597
> Code: 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66
> 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 58 00 00 00 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:00007ffd09085778 EFLAGS: 00000206 ORIG_RAX: 0000000000000058
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000046a597
> RDX: 0000000000000000 RSI: 00000000004e40f9 RDI: 00007ffd09085810
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000014
> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
> R13: 0000000000000000 R14: 00007ffd09085810 R15: 00007ffd090857cc
> ----------------
> Code disassembly (best guess):
> 0: 65 48 8b 14 25 40 70 mov %gs:0x17040,%rdx
> 7: 01 00
> 9: 81 e1 00 01 00 00 and $0x100,%ecx
> f: a9 00 01 ff 00 test $0xff0100,%eax
> 14: 74 0e je 0x24
> 16: 85 c9 test %ecx,%ecx
> 18: 74 35 je 0x4f
> 1a: 8b 82 34 15 00 00 mov 0x1534(%rdx),%eax
> 20: 85 c0 test %eax,%eax
> 22: 74 2b je 0x4f
> 24: 8b 82 10 15 00 00 mov 0x1510(%rdx),%eax
> * 2a: 83 f8 02 cmp $0x2,%eax <-- trapping instruction
> 2d: 75 20 jne 0x4f
> 2f: 48 8b 8a 18 15 00 00 mov 0x1518(%rdx),%rcx
> 36: 8b 92 14 15 00 00 mov 0x1514(%rdx),%edx
> 3c: 48 8b 01 mov (%rcx),%rax
> 3f: 48 rex.W%
>
Move releasing of bdi to workqueue work to make it safe to sync rcu.
Only for thoughts now.
+++ x/mm/backing-dev.c
@@ -959,10 +959,11 @@ void bdi_unregister(struct backing_dev_i
}
}
-static void release_bdi(struct kref *ref)
+static void bdi_release_workfn(struct work_struct *work)
{
- struct backing_dev_info *bdi =
- container_of(ref, struct backing_dev_info, refcnt);
+ struct backing_dev_info *bdi;
+
+ bdi = container_of(work, struct backing_dev_info, release_work);
if (test_bit(WB_registered, &bdi->wb.state))
bdi_unregister(bdi);
@@ -971,6 +972,16 @@ static void release_bdi(struct kref *ref
kfree(bdi);
}
+static void release_bdi(struct kref *ref)
+{
+ struct backing_dev_info *bdi;
+
+ bdi = container_of(ref, struct backing_dev_info, refcnt);
+
+ INIT_WORK(&bdi->release_work, bdi_release_workfn);
+ queue_work(system_unbound_wq, &bdi->release_work);
+}
+
void bdi_put(struct backing_dev_info *bdi)
{
kref_put(&bdi->refcnt, release_bdi);