linux-kernel - Re: BUG: KASAN lib/test

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Date:   Sat, 05 Dec 2020 02:22:47 +0530
From:   Jeffrin Jose T <jeffrin@...agiritech.edu.in>
To:     Marco Elver <elver@...gle.com>
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: BUG: KASAN lib/test_kasan.c

On Fri, 2020-12-04 at 21:29 +0100, Marco Elver wrote:
> On Fri, 4 Dec 2020 at 19:56, Jeffrin Jose T
> <jeffrin@...agiritech.edu.in> wrote:
> > hello,
> > 
> >  detected   KASAN   BUG
> > 
> > [ related information ]
> > 
> > -------------------x-------------------x------------------------>
> > [   43.616259] BUG: KASAN: vmalloc-out-of-bounds in
> > vmalloc_oob+0x146/0x2c0
> > 
> > (gdb) l *vmalloc_oob+0x146/0x2c0
> > 0xffffffff81b8b0b0 is in vmalloc_oob (lib/test_kasan.c:764).
> 
> This is the KASAN test. It's a feature, not a bug. ;-)
> 
> > 759             kfree_sensitive(ptr);
> > 760             KUNIT_EXPECT_KASAN_FAIL(test,
> > kfree_sensitive(ptr));
> > 761     }
> > 762
> > 763     static void vmalloc_oob(struct kunit *test)
> > 764     {
> > 765             void *area;
> > 766
> > 767             if (!IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
> > 768                     kunit_info(test, "CONFIG_KASAN_VMALLOC is
> > not
> > enabled.");
> > (gdb) l *vmalloc_oob+0x146
> > 0xffffffff81b8b1f6 is in vmalloc_oob (lib/test_kasan.c:779).
> > 774              * The MMU will catch that and crash us.
> > 775              */
> > 776             area = vmalloc(3000);
> > 777             KUNIT_ASSERT_NOT_ERR_OR_NULL(test, area);
> > 778
> > 779             KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char
> > *)area)[3100]);
> > 780             vfree(area);
> > 781     }
> > 782
> > 783     static struct kunit_case kasan_kunit_test_cases[] = {
> > ----------------x-----------------------------x--------------------
> > >
> > 
> > Reported by: Jeffrin Jose T <jeffrin@...agiritech.edu.in>
> 
> Which CI system is reporting these?
> 
> If you look, this is the KASAN test, and the report is very much
> intended since it's testing KASAN. Please blacklist the KASAN test
> (and any other tests testing debugging tools).
> 
> Thanks,
> -- Marco

gdb session was started by me.  (gdb ./vmlinux)

portion from dmesg output is as follows
--------------------x------------------------x-------------------------
-->
[   43.616259] BUG: KASAN: vmalloc-out-of-bounds in
vmalloc_oob+0x146/0x2c0
[   43.630470] Read of size 1 at addr ffffc9000006ec1c by task
kunit_try_catch/193

[   43.659055] CPU: 2 PID: 193 Comm: kunit_try_catch Tainted: G    B  
5.10.0-rc6+ #10
[   43.659070] Hardware name: ASUSTeK COMPUTER INC. VivoBook 15_ASUS
Laptop X507UAR/X507UAR, BIOS X507UAR.203 05/31/2018
[   43.659080] Call Trace:
[   43.659105]  dump_stack+0x119/0x179
[   43.659131]  print_address_description.constprop.0+0x1c/0x210
[   43.659163]  ? vmalloc_oob+0x146/0x2c0
[   43.659185]  kasan_report.cold+0x1f/0x37
[   43.659210]  ? vmalloc_oob+0x146/0x2c0
[   43.659234]  vmalloc_oob+0x146/0x2c0
[   43.659259]  ? kasan_global_oob+0x280/0x280
[   43.659287]  ? kunit_fail_assert_format+0xa0/0xa0
[   43.659313]  ? lock_release+0xb2/0x730
[   43.659334]  ? __kthread_parkme+0xa1/0x120
[   43.659356]  ? lock_acquired+0xb4/0x5b0
[   43.659379]  ? lock_downgrade+0x3d0/0x3d0
[   43.659403]  ? lock_contended+0x6e0/0x6e0
[   43.659423]  ? do_raw_spin_lock+0x1b0/0x1b0
[   43.659447]  ? io_schedule_timeout+0xb0/0xb0
[   43.659467]  ? static_obj+0x31/0x80
[   43.659492]  ? lockdep_hardirqs_on_prepare+0xe/0x240
[   43.659517]  ? memcg_accounted_kmem_cache+0x1b0/0x1b0
[   43.659542]  kunit_try_run_case+0xa6/0x150
[   43.659567]  ? kunit_catch_run_case+0x170/0x170
[   43.659591]  ? kunit_try_catch_throw+0x40/0x40
[   43.659617]  kunit_generic_run_threadfn_adapter+0x2e/0x50
[   43.659637]  kthread+0x232/0x260
[   43.659659]  ? __kthread_bind_mask+0x90/0x90
[   43.659684]  ret_from_fork+0x22/0x30


[   43.686511] Memory state around the buggy address:
[   43.700445]  ffffc9000006eb00: 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00
[   43.714559]  ffffc9000006eb80: 00 00 00 00 00 00 00 f8 f8 f8 f8 f8
f8 f8 f8 f8
[   43.728725] >ffffc9000006ec00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
f8 f8 f8 f8
[   43.742808]                             ^
[   43.757156]  ffffc9000006ec80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
f8 f8 f8 f8
[   43.771845]  ffffc9000006ed00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
f8 f8 f8 f8
[   43.785957]
==================================================================

-------------------x-----------------------------x---------------------
---------->


-- 
software engineer
rajagiri school of engineering and technology - autonomous