linux-kernel - Re: [PATCH] crypto: qat - Fix KASAN stack-out-of-bounds bug in adf

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Date:   Fri, 28 Sep 2018 13:10:23 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Waiman Long <longman@...hat.com>
Cc:     Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
        "David S. Miller" <davem@...emloft.net>, qat-linux@...el.com,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Conor McLoughlin <conor.mcloughlin@...el.com>
Subject: Re: [PATCH] crypto: qat - Fix KASAN stack-out-of-bounds bug in
 adf_probe()

On Sat, Sep 22, 2018 at 08:41:55PM -0400, Waiman Long wrote:
> The following KASAN warning was printed when booting a 64-bit kernel
> on some systems with Intel CPUs:
> 
> [   44.512826] ==================================================================
> [   44.520165] BUG: KASAN: stack-out-of-bounds in find_first_bit+0xb0/0xc0
> [   44.526786] Read of size 8 at addr ffff88041e02fc50 by task kworker/0:2/124
> 
> [   44.535253] CPU: 0 PID: 124 Comm: kworker/0:2 Tainted: G               X --------- ---  4.18.0-12.el8.x86_64+debug #1
> [   44.545858] Hardware name: Intel Corporation PURLEY/PURLEY, BIOS BKVDTRL1.86B.0005.D08.1712070559 12/07/2017
> [   44.555682] Workqueue: events work_for_cpu_fn
> [   44.560043] Call Trace:
> [   44.562502]  dump_stack+0x9a/0xe9
> [   44.565832]  print_address_description+0x65/0x22e
> [   44.570683]  ? find_first_bit+0xb0/0xc0
> [   44.570689]  kasan_report.cold.6+0x92/0x19f
> [   44.578726]  find_first_bit+0xb0/0xc0
> [   44.578737]  adf_probe+0x9eb/0x19a0 [qat_c62x]
> [   44.578751]  ? adf_remove+0x110/0x110 [qat_c62x]
> [   44.591490]  ? mark_held_locks+0xc8/0x140
> [   44.591498]  ? _raw_spin_unlock+0x30/0x30
> [   44.591505]  ? trace_hardirqs_on_caller+0x381/0x570
> [   44.604418]  ? adf_remove+0x110/0x110 [qat_c62x]
> [   44.604427]  local_pci_probe+0xd4/0x180
> [   44.604432]  ? pci_device_shutdown+0x110/0x110
> [   44.617386]  work_for_cpu_fn+0x51/0xa0
> [   44.621145]  process_one_work+0x8fe/0x16e0
> [   44.625263]  ? pwq_dec_nr_in_flight+0x2d0/0x2d0
> [   44.629799]  ? lock_acquire+0x14c/0x400
> [   44.633645]  ? move_linked_works+0x12e/0x2a0
> [   44.637928]  worker_thread+0x536/0xb50
> [   44.641690]  ? __kthread_parkme+0xb6/0x180
> [   44.645796]  ? process_one_work+0x16e0/0x16e0
> [   44.650160]  kthread+0x30c/0x3d0
> [   44.653400]  ? kthread_create_worker_on_cpu+0xc0/0xc0
> [   44.658457]  ret_from_fork+0x3a/0x50
> 
> [   44.663557] The buggy address belongs to the page:
> [   44.668350] page:ffffea0010780bc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
> [   44.676356] flags: 0x17ffffc0000000()
> [   44.680023] raw: 0017ffffc0000000 ffffea0010780bc8 ffffea0010780bc8 0000000000000000
> [   44.687769] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
> [   44.695510] page dumped because: kasan: bad access detected
> 
> [   44.702578] Memory state around the buggy address:
> [   44.707372]  ffff88041e02fb00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [   44.714593]  ffff88041e02fb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [   44.721810] >ffff88041e02fc00: 00 00 00 00 00 00 f1 f1 f1 f1 04 f2 f2 f2 f2 f2
> [   44.729028]                                                  ^
> [   44.734864]  ffff88041e02fc80: f2 f2 00 00 00 00 f3 f3 f3 f3 00 00 00 00 00 00
> [   44.742082]  ffff88041e02fd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [   44.749299] ==================================================================
> 
> Looking into the code:
> 
>   int ret, bar_mask;
>     :
>   for_each_set_bit(bar_nr, (const unsigned long *)&bar_mask,
> 
> It is casting a 32-bit integer pointer to a 64-bit unsigned long
> pointer. There are two problems here. First, the 32-bit pointer address
> may not be 64-bit aligned. Secondly, it is accessing an extra 4 bytes.
> 
> This is fixed by changing the bar_mask type to unsigned long.
> 
> Signed-off-by: Waiman Long <longman@...hat.com>

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt