On Wed, Apr 26, 2017 at 3:59 PM, Paul E. McKenney <paul...@linux.vnet.ibm.com> wrote: > On Wed, Apr 26, 2017 at 02:34:15PM +0200, Andrey Konovalov wrote: >> Hi, >> >> I've got the following error report while fuzzing the kernel with syzkaller. >> >> On commit 5a7ad1146caa895ad718a534399e38bd2ba721b7 (4.11-rc8). >> >> Unfortunately it's not reproducible. >> >> I'm not sure whether is is an issue with rcu or ipv6. >> >> ================================================================== >> BUG: KASAN: use-after-free in __call_rcu.constprop.77+0x13be/0x1640 > > Does building with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y show any splats? > (Yeah, kind of a stupid question if it is not reproducible, but had > to ask!)
Hi Paul, I'll try enabling this config. In the meantime, while I was trying to reproduce this issue, I got this warning: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 4590 at kernel/rcu/tree.c:2919 rcu_do_batch.isra.65+0x845/0xbd0 Modules linked in: CPU: 0 PID: 4590 Comm: syz-executor Not tainted 4.11.0-rc8+ #270 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:16 dump_stack+0x192/0x22d lib/dump_stack.c:52 __warn+0x19f/0x1e0 kernel/panic.c:549 warn_slowpath_null+0x2c/0x40 kernel/panic.c:584 rcu_do_batch.isra.65+0x845/0xbd0 kernel/rcu/tree.c:2919 invoke_rcu_callbacks kernel/rcu/tree.c:3142 __rcu_process_callbacks kernel/rcu/tree.c:3109 rcu_process_callbacks+0x23f/0x810 kernel/rcu/tree.c:3126 __do_softirq+0x253/0x78b kernel/softirq.c:284 invoke_softirq kernel/softirq.c:364 irq_exit+0x149/0x180 kernel/softirq.c:405 exiting_irq ./arch/x86/include/asm/apic.h:657 smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:962 apic_timer_interrupt+0x89/0x90 RIP: 0010:do_anonymous_page mm/memory.c:2962 RIP: 0010:handle_pte_fault mm/memory.c:3721 RIP: 0010:__handle_mm_fault+0xdab/0x1c00 mm/memory.c:3841 RSP: 0018:ffff88006a02f7d0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 RAX: 000000000005dab0 RBX: 1ffff1000d405f00 RCX: 1ffff1000d28cd3f RDX: dffffc0000000000 RSI: 8000000000000025 RDI: ffff8800694669f8 RBP: ffff88006a02f9a8 R08: 00000000014280ca R09: 1ffff1000d405eb0 R10: ffff88006a02f660 R11: dffffc0000000000 R12: ffff88006a02f8e0 R13: ffff88006a02f980 R14: ffff8800694669b0 R15: ffff880069466a00 </IRQ> handle_mm_fault+0x1aa/0x450 mm/memory.c:3878 faultin_page mm/gup.c:408 __get_user_pages+0x606/0x14a0 mm/gup.c:607 populate_vma_page_range+0xd9/0x100 mm/gup.c:1062 __mm_populate+0x278/0x540 mm/gup.c:1112 mm_populate ./include/linux/mm.h:2132 vm_mmap_pgoff+0x258/0x280 mm/util.c:314 SYSC_mmap_pgoff mm/mmap.c:1503 SyS_mmap_pgoff+0x22c/0x5e0 mm/mmap.c:1461 SYSC_mmap arch/x86/kernel/sys_x86_64.c:96 SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:87 entry_SYSCALL_64_fastpath+0x1a/0xa9 arch/x86/entry/entry_64.S:204 RIP: 0033:0x4458e9 RSP: 002b:00007f3a15ce4b58 EFLAGS: 00000282 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f3a15ce5700 RCX: 00000000004458e9 RDX: 0000000000000002 RSI: 00000000009b8000 RDI: 0000000020000000 RBP: 0000000000000000 R08: ffffffffffffffff R09: 8000000000000000 R10: 0000000000008032 R11: 0000000000000282 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f3a15ce59c0 R15: 00007f3a15ce5700 ---[ end trace e36457085170396e ]--- > > Thanx, Paul > >> kernel/rcu/tree.c:3269 at addr ffff88003b842280 >> Write of size 8 by task kworker/u10:1/180 >> CPU: 2 PID: 180 Comm: kworker/u10:1 Not tainted 4.11.0-rc8+ #270 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> Workqueue: events_unbound call_usermodehelper_exec_work >> Call Trace: >> __dump_stack lib/dump_stack.c:16 [inline] >> dump_stack+0x192/0x22d lib/dump_stack.c:52 >> kasan_object_err+0x1c/0x70 mm/kasan/report.c:164 >> print_address_description mm/kasan/report.c:202 [inline] >> kasan_report_error mm/kasan/report.c:291 [inline] >> kasan_report+0x252/0x510 mm/kasan/report.c:347 >> __asan_report_store8_noabort+0x17/0x20 mm/kasan/report.c:373 >> __call_rcu.constprop.77+0x13be/0x1640 kernel/rcu/tree.c:3269 >> call_rcu_sched+0x12/0x20 kernel/rcu/tree.c:3288 >> free_pid+0x446/0x5d0 kernel/pid.c:293 >> __change_pid+0x2a1/0x3d0 kernel/pid.c:411 >> detach_pid+0x1f/0x30 kernel/pid.c:416 >> __unhash_process kernel/exit.c:74 [inline] >> __exit_signal kernel/exit.c:155 [inline] >> release_task+0xbb0/0x1d90 kernel/exit.c:199 >> wait_task_zombie kernel/exit.c:1230 [inline] >> wait_consider_task+0x11fe/0x3410 kernel/exit.c:1458 >> do_wait_thread kernel/exit.c:1521 [inline] >> do_wait+0x3ea/0x8e0 kernel/exit.c:1592 >> SYSC_wait4 kernel/exit.c:1720 [inline] >> SyS_wait4+0x208/0x340 kernel/exit.c:1689 >> call_usermodehelper_exec_sync kernel/kmod.c:292 [inline] >> call_usermodehelper_exec_work+0x1a7/0x2b0 kernel/kmod.c:329 >> process_one_work+0x9f7/0x1580 kernel/workqueue.c:2097 >> worker_thread+0x1df/0x14b0 kernel/workqueue.c:2231 >> kthread+0x31f/0x3f0 kernel/kthread.c:231 >> ret_from_fork+0x2c/0x40 arch/x86/entry/entry_64.S:430 >> Object at ffff88003b842018, in cache kmalloc-1024 size: 1024 >> Allocated: >> PID = 1 >> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 >> save_stack+0x43/0xd0 mm/kasan/kasan.c:513 >> set_track mm/kasan/kasan.c:525 [inline] >> kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:616 >> kmem_cache_alloc_trace+0x61/0x170 mm/slub.c:2745 >> kmalloc include/linux/slab.h:490 [inline] >> kzalloc include/linux/slab.h:663 [inline] >> ipv6_add_dev+0x199/0x1380 net/ipv6/addrconf.c:380 >> addrconf_init+0xd0/0x29a net/ipv6/addrconf.c:6405 >> inet6_init+0x2f6/0x584 net/ipv6/af_inet6.c:962 >> do_one_initcall+0xf3/0x380 init/main.c:792 >> do_initcall_level init/main.c:858 [inline] >> do_initcalls init/main.c:866 [inline] >> do_basic_setup init/main.c:884 [inline] >> kernel_init_freeable+0x54d/0x622 init/main.c:1035 >> kernel_init+0x13/0x180 init/main.c:959 >> ret_from_fork+0x2c/0x40 arch/x86/entry/entry_64.S:430 >> Freed: >> PID = 6479 >> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 >> save_stack+0x43/0xd0 mm/kasan/kasan.c:513 >> set_track mm/kasan/kasan.c:525 [inline] >> kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:589 >> slab_free_hook mm/slub.c:1357 [inline] >> slab_free_freelist_hook mm/slub.c:1379 [inline] >> slab_free mm/slub.c:2961 [inline] >> kfree+0x91/0x190 mm/slub.c:3882 >> in6_dev_finish_destroy_rcu+0x97/0xc0 net/ipv6/addrconf_core.c:150 >> __rcu_reclaim kernel/rcu/rcu.h:118 [inline] >> rcu_do_batch.isra.65+0x6de/0xbd0 kernel/rcu/tree.c:2879 >> invoke_rcu_callbacks kernel/rcu/tree.c:3142 [inline] >> __rcu_process_callbacks kernel/rcu/tree.c:3109 [inline] >> rcu_process_callbacks+0x23f/0x810 kernel/rcu/tree.c:3126 >> __do_softirq+0x253/0x78b kernel/softirq.c:284 >> Memory state around the buggy address: >> ffff88003b842180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff88003b842200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> >ffff88003b842280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ^ >> ffff88003b842300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff88003b842380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ================================================================== >> >
