Re: [PATCH] module: Fix load failure when CONFIG_STRICT_MODULE_RWX is diabled

[Jessica Yu]

+++ He Zhe [14/08/19 09:56 +0800]:
> On 8/14/19 1:59 AM, Jessica Yu wrote:
> > +++ zhe.he@xxxxxxxxxxxxx [10/08/19 15:22 +0800]:
> > > From: He Zhe <zhe.he@xxxxxxxxxxxxx>
> > >
> > > 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@xxxxxxxxxxxxx>
> >
> > 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