** Description changed:
==================================================================
BUG: KASan: use after free in task_numa_find_cpu+0x64c/0x890 at addr
ffff880dd393ecd8
Read of size 8 by task qemu-system-x86/3998900
=============================================================================
BUG kmalloc-128 (Tainted: G B ): kasan: bad access detected
-----------------------------------------------------------------------------
INFO: Allocated in task_numa_fault+0xc1b/0xed0 age=41980 cpu=18 pid=3998890
__slab_alloc+0x4f8/0x560
__kmalloc+0x1eb/0x280
task_numa_fault+0xc1b/0xed0
do_numa_page+0x192/0x200
handle_mm_fault+0x808/0x1160
__do_page_fault+0x218/0x750
do_page_fault+0x1a/0x70
page_fault+0x28/0x30
SyS_poll+0x66/0x1a0
system_call_fastpath+0x1a/0x1f
INFO: Freed in task_numa_free+0x1d2/0x200 age=62 cpu=18 pid=0
__slab_free+0x2ab/0x3f0
kfree+0x161/0x170
task_numa_free+0x1d2/0x200
finish_task_switch+0x1d2/0x210
__schedule+0x5d4/0xc60
schedule_preempt_disabled+0x40/0xc0
cpu_startup_entry+0x2da/0x340
start_secondary+0x28f/0x360
INFO: Slab 0xffffea00374e4f00 objects=37 used=17 fp=0xffff880dd393ecb0
flags=0x6ffff0000004080
INFO: Object 0xffff880dd393ecb0 @offset=11440 fp=0xffff880dd393f700
Bytes b4 ffff880dd393eca0: 0c 00 00 00 18 00 00 00 af 63 3a 04 01 00 00 00
.........c:.....
Object ffff880dd393ecb0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
kkkkkkkkkkkkkkkk
Object ffff880dd393ecc0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
kkkkkkkkkkkkkkkk
Object ffff880dd393ecd0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
kkkkkkkkkkkkkkkk
Object ffff880dd393ece0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
kkkkkkkkkkkkkkkk
Object ffff880dd393ecf0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
kkkkkkkkkkkkkkkk
Object ffff880dd393ed00: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
kkkkkkkkkkkkkkkk
Object ffff880dd393ed10: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
kkkkkkkkkkkkkkkk
Object ffff880dd393ed20: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5
kkkkkkkkkkkkkkk.
CPU: 61 PID: 3998900 Comm: qemu-system-x86 Tainted: G B
3.13.0-65-generic #105
Hardware name: Supermicro X8QB6/X8QB6, BIOS 2.0c 06/11/2
ffffea00374e4f00 ffff8816c572b420 ffffffff81a6ce35 ffff88045f00f500
ffff8816c572b450 ffffffff81244aed ffff88045f00f500 ffffea00374e4f00
ffff880dd393ecb0 0000000000000012 ffff8816c572b478 ffffffff8124ac36
Call Trace:
[<ffffffff81a6ce35>] dump_stack+0x45/0x56
[<ffffffff81244aed>] print_trailer+0xfd/0x170
[<ffffffff8124ac36>] object_err+0x36/0x40
[<ffffffff8124cbf9>] kasan_report_error+0x1e9/0x3a0
[<ffffffff8124d260>] kasan_report+0x40/0x50
[<ffffffff810dda7c>] ? task_numa_find_cpu+0x64c/0x890
[<ffffffff8124bee9>] __asan_load8+0x69/0xa0
[<ffffffff814f5c38>] ? find_next_bit+0xd8/0x120
[<ffffffff810dda7c>] task_numa_find_cpu+0x64c/0x890
[<ffffffff810de16c>] task_numa_migrate+0x4ac/0x7b0
[<ffffffff810de523>] numa_migrate_preferred+0xb3/0xc0
[<ffffffff810e0b88>] task_numa_fault+0xb88/0xed0
[<ffffffff8120ef02>] do_numa_page+0x192/0x200
[<ffffffff81211038>] handle_mm_fault+0x808/0x1160
[<ffffffff810d7dbd>] ? sched_clock_cpu+0x10d/0x160
[<ffffffff81068c52>] ? native_load_tls+0x82/0xa0
[<ffffffff81a7bd68>] __do_page_fault+0x218/0x750
[<ffffffff810c2186>] ? hrtimer_try_to_cancel+0x76/0x160
[<ffffffff81a6f5e7>] ? schedule_hrtimeout_range_clock.part.24+0xf7/0x1c0
[<ffffffff81a7c2ba>] do_page_fault+0x1a/0x70
[<ffffffff81a772e8>] page_fault+0x28/0x30
[<ffffffff8128cbd4>] ? do_sys_poll+0x1c4/0x6d0
[<ffffffff810e64f6>] ? enqueue_task_fair+0x4b6/0xaa0
[<ffffffff810233c9>] ? sched_clock+0x9/0x10
[<ffffffff810cf70a>] ? resched_task+0x7a/0xc0
[<ffffffff810d0663>] ? check_preempt_curr+0xb3/0x130
[<ffffffff8128b5c0>] ? poll_select_copy_remaining+0x170/0x170
[<ffffffff810d3bc0>] ? wake_up_state+0x10/0x20
[<ffffffff8112a28f>] ? drop_futex_key_refs.isra.14+0x1f/0x90
[<ffffffff8112d40e>] ? futex_requeue+0x3de/0xba0
[<ffffffff8112e49e>] ? do_futex+0xbe/0x8f0
[<ffffffff81022c89>] ? read_tsc+0x9/0x20
[<ffffffff8111bd9d>] ? ktime_get_ts+0x12d/0x170
[<ffffffff8108f699>] ? timespec_add_safe+0x59/0xe0
[<ffffffff8128d1f6>] SyS_poll+0x66/0x1a0
[<ffffffff81a830dd>] system_call_fastpath+0x1a/0x1f
Memory state around the buggy address:
ffff880dd393eb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff880dd393ec00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff880dd393ec80: fc fc fc fc fc fc fb fb fb fb fb fb fb fb fb fb
^
ffff880dd393ed00: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
ffff880dd393ed80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
--------------------------8<--------------------------
- $ addr2line 0xffffffff810dda7c -e
usr/lib/debug/boot/vmlinux-3.13.0-65-generic -f -i
+ $ addr2line 0xffffffff810dda7c -e
usr/lib/debug/boot/vmlinux-3.13.0-65-generic -f -i
task_numa_compare
/home/gavin/os/ubuntu-trusty-amd64/kernel/sched/fair.c:1084
task_numa_find_cpu
/home/gavin/os/ubuntu-trusty-amd64/kernel/sched/fair.c:1170
-
1083 if (cur->numa_group == env->p->numa_group) {
1084 imp = taskimp + task_weight(cur, env->src_nid) -
1085 task_weight(cur, env->dst_nid);
+ In short, this is the use-after-free bug happens on the
+ task_struct->numa_faults which is freed by the task_numa_free called by
+ the finish_task_switch when the process is exiting. While the numa
+ balance mechanism is triggering the do_numa_page fault and need to read
+ the task_struct->numa_faults to determine if the current exiting process
+ is needed to migrate to the other CPU for better memory access
+ performance because of shorter distance to access memory on the other
+ node.
- In short, this is the use-after-free bug happens on the
task_struct->numa_faults which is freed by the task_numa_free called by the
finish_task_switch when the process is exiting. While the numa balance
mechanism is triggering the do_numa_page fault and need to read the
task_struct->numa_faults to determine if the current exiting process is needed
to migrate to the other CPU for better memory access performance because of
shorter distance to access memory on the other node.
+ The bug was found by the Ubuntu-3.13.0-65 with Kasan backported
+ binary package:
http://kernel.ubuntu.com/~gavinguo/kasan/Ubuntu-3.13.0-65.105/
+
+ source code: http://kernel.ubuntu.com/git/gavinguo/ubuntu-trusty-
+ amd64.git/log/?h=Ubuntu-3.13.0-65-kasan
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https://bugs.launchpad.net/bugs/1527643
Title:
use after free of task_struct->numa_faults in task_numa_find_cpu
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