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 <sunhao.th@xxxxxxxxx> 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);
