linux-kernel - Re: [PATCH] module: Fix load failure when CONFIG_STRICT_MODULE

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Message-ID: <20190820123247.GA4639@linux-8ccs>
Date:   Tue, 20 Aug 2019 14:32:47 +0200
From:   Jessica Yu <jeyu@...nel.org>
To:     He Zhe <zhe.he@...driver.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] module: Fix load failure when CONFIG_STRICT_MODULE_RWX
 is diabled

+++ He Zhe [14/08/19 09:56 +0800]:
>
>
>On 8/14/19 1:59 AM, Jessica Yu wrote:
>> +++ zhe.he@...driver.com [10/08/19 15:22 +0800]:
>>> From: He Zhe <zhe.he@...driver.com>
>>>
>>> When loading modules with CONFIG_ARCH_HAS_STRICT_MODULE_RWX enabled and
>>> CONFIG_STRICT_MODULE_RWX disabled, the memory allocated for modules would
>>> not be page-aligned and cause the following BUG during frob_text.
>>>
>>> ------------[ cut here ]------------
>>> kernel BUG at kernel/module.c:1907!
>>> Internal error: Oops - BUG: 0 [#1] ARM
>>> Modules linked in:
>>> CPU: 0 PID: 89 Comm: systemd-modules Not tainted 5.3.0-rc2 #1
>>> Hardware name: ARM-Versatile (Device Tree Support)
>>> PC is at frob_text.constprop.0+0x2c/0x40
>>> LR is at load_module+0x14b4/0x1d28
>>> pc : [<c0082930>]    lr : [<c0084bb0>]    psr: 20000013
>>> sp : ce44fe58  ip : 00000000  fp : 00000000
>>> r10: 00000000  r9 : ce44feb8  r8 : 00000000
>>> r7 : 00000001  r6 : bf00032c  r5 : ce44ff40  r4 : bf000320
>>> r3 : bf000400  r2 : 00000fff  r1 : 00000220  r0 : bf000000
>>> Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
>>> Control: 00093177  Table: 0e4c0000  DAC: 00000051
>>> Process systemd-modules (pid: 89, stack limit = 0x9fccc8dc)
>>> Stack: (0xce44fe58 to 0xce450000)
>>> fe40:                                                       00000000 cf1b05b8
>>> fe60: 00000001 ce47cf08 bf002754 c07ae5d8 d0a2a484 bf002060 bf0004f8 00000000
>>> fe80: b6d17910 c017cf1c ce47cf00 d0a29000 ce47cf00 ce44ff34 000014fc 00000000
>>> fea0: 00000000 00000000 bf00025c 00000001 00000000 00000000 6e72656b 00006c65
>>> fec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
>>> fee0: 00000000 00000000 00000000 00000000 00000000 c0ac9048 7fffffff 00000000
>>> ff00: b6d17910 00000005 0000017b c0009208 ce44e000 00000000 b6ebfe54 c008562c
>>> ff20: 7fffffff 00000000 00000003 cefd28f8 00000001 d0a29000 000014fc 00000000
>>> ff40: d0a292cb d0a29380 d0a29000 000014fc d0a29f0c d0a29d90 d0a29a60 00000520
>>> ff60: 00000710 00000718 00000826 00000000 00000000 00000000 00000708 00000023
>>> ff80: 00000024 0000001c 00000000 00000016 00000000 c0ac9048 0041c620 00000000
>>> ffa0: 00000000 c0009000 0041c620 00000000 00000005 b6d17910 00000000 00000000
>>> ffc0: 0041c620 00000000 00000000 0000017b 0041f078 00000000 004098b0 b6ebfe54
>>> ffe0: bedb6bc8 bedb6bb8 b6d0f91c b6c945a0 60000010 00000005 00000000 00000000
>>> [<c0082930>] (frob_text.constprop.0) from [<c0084bb0>] (load_module+0x14b4/0x1d28)
>>> [<c0084bb0>] (load_module) from [<c008562c>] (sys_finit_module+0xa0/0xc4)
>>> [<c008562c>] (sys_finit_module) from [<c0009000>] (ret_fast_syscall+0x0/0x50)
>>> Exception stack(0xce44ffa8 to 0xce44fff0)
>>> ffa0:                   0041c620 00000000 00000005 b6d17910 00000000 00000000
>>> ffc0: 0041c620 00000000 00000000 0000017b 0041f078 00000000 004098b0 b6ebfe54
>>> ffe0: bedb6bc8 bedb6bb8 b6d0f91c b6c945a0
>>> Code: e7f001f2 e5931008 e1110002 0a000001 (e7f001f2)
>>> ---[ end trace e904557128d9aed5 ]---
>>>
>>> This patch enables page-aligned allocation when
>>> CONFIG_ARCH_HAS_STRICT_MODULE_RWX is enabled.
>>>
>>> Fixes: 93651f80dcb6 ("modules: fix compile error if don't have strict module rwx")
>>> Signed-off-by: He Zhe <zhe.he@...driver.com>
>>
>> Hi!
>>
>> I have already committed a fix for this to modules-next and plan to
>> send a pull request next week.
>
>Thanks for pointing out :)
>
>https://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux.git/commit/?h=modules-next&id=38f054d549a869f22a02224cd276a27bf14b6171
>
>But I'd suggest we should keep the case of "define debug_align(X) (X)" for all
>the rest arches without CONFIG_HAS_STRICT_MODULE_RWX ability, which would save
>people who are sensitive to system size a lot of memory when using modules,
>especially for embedded systems, as this patch did. This seems the original
>intention of this #ifdef... statement and still valid for now.
>
>Zhe

Fair enough! Could you please respin this patch and base it on top of
modules-next? I would like to avoid rebasing the tree. 

Thank you!

Jessica