linux-kernel - Re: [PATCH v2] ARM: socfpga: Fix crash with CONFIG_FORTIRY

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Date:   Fri, 19 Nov 2021 14:37:24 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Dinh Nguyen <dinguyen@...nel.org>
Cc:     Takashi Iwai <tiwai@...e.de>, Kees Cook <keescook@...omium.org>,
        "Ivan T . Ivanov" <iivanov@...e.de>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ARM: socfpga: Fix crash with CONFIG_FORTIRY_SOURCE

On Thu, 18 Nov 2021 23:08:27 +0100,
Dinh Nguyen wrote:
> 
> Hi Iwai,
> 
> Should this have the following tag:
> 
> Fixes: 9c4566a117a6 ("ARM: socfpga: Enable SMP for socfpga")
> 
> As well?

Yes, that'd be helpful, too.


thanks,

Takashi

> 
> On 11/18/21 8:25 AM, Takashi Iwai wrote:
> > When CONFIG_FORTIFY_SOURCE is set, memcpy() checks the potential
> > buffer overflow and panics.  The code in sofcpga bootstrapping
> > contains the memcpy() calls are mistakenly translated as the shorter
> > size, hence it triggers a panic as if it were overflowing.
> >
> > This patch changes the secondary_trampoline and *_end definitions
> > to arrays for avoiding the false-positive crash above.
> >
> > Suggested-by: Kees Cook <keescook@...omium.org>
> > Buglink: https://bugzilla.suse.com/show_bug.cgi?id=1192473
> > Link: https://lore.kernel.org/r/20211117193244.31162-1-tiwai@suse.de
> > Signed-off-by: Takashi Iwai <tiwai@...e.de>
> > ---
> >
> > v1->v2: Use arrays for trampoline area instead of hackish workaround
> > 	with __NO_FORTIFY
> >
> >   arch/arm/mach-socfpga/core.h    | 2 +-
> >   arch/arm/mach-socfpga/platsmp.c | 8 ++++----
> >   2 files changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/arm/mach-socfpga/core.h b/arch/arm/mach-socfpga/core.h
> > index fc2608b18a0d..18f01190dcfd 100644
> > --- a/arch/arm/mach-socfpga/core.h
> > +++ b/arch/arm/mach-socfpga/core.h
> > @@ -33,7 +33,7 @@ extern void __iomem *sdr_ctl_base_addr;
> >   u32 socfpga_sdram_self_refresh(u32 sdr_base);
> >   extern unsigned int socfpga_sdram_self_refresh_sz;
> >   -extern char secondary_trampoline, secondary_trampoline_end;
> > +extern char secondary_trampoline[], secondary_trampoline_end[];
> >     extern unsigned long socfpga_cpu1start_addr;
> >   diff --git a/arch/arm/mach-socfpga/platsmp.c
> > b/arch/arm/mach-socfpga/platsmp.c
> > index fbb80b883e5d..201191cf68f3 100644
> > --- a/arch/arm/mach-socfpga/platsmp.c
> > +++ b/arch/arm/mach-socfpga/platsmp.c
> > @@ -20,14 +20,14 @@
> >     static int socfpga_boot_secondary(unsigned int cpu, struct
> > task_struct *idle)
> >   {
> > -	int trampoline_size = &secondary_trampoline_end - &secondary_trampoline;
> > +	int trampoline_size = secondary_trampoline_end - secondary_trampoline;
> >     	if (socfpga_cpu1start_addr) {
> >   		/* This will put CPU #1 into reset. */
> >   		writel(RSTMGR_MPUMODRST_CPU1,
> >   		       rst_manager_base_addr + SOCFPGA_RSTMGR_MODMPURST);
> >   -		memcpy(phys_to_virt(0), &secondary_trampoline,
> > trampoline_size);
> > +		memcpy(phys_to_virt(0), secondary_trampoline, trampoline_size);
> >     		writel(__pa_symbol(secondary_startup),
> >   		       sys_manager_base_addr + (socfpga_cpu1start_addr & 0x000000ff));
> > @@ -45,12 +45,12 @@ static int socfpga_boot_secondary(unsigned int cpu, struct task_struct *idle)
> >     static int socfpga_a10_boot_secondary(unsigned int cpu, struct
> > task_struct *idle)
> >   {
> > -	int trampoline_size = &secondary_trampoline_end - &secondary_trampoline;
> > +	int trampoline_size = secondary_trampoline_end - secondary_trampoline;
> >     	if (socfpga_cpu1start_addr) {
> >   		writel(RSTMGR_MPUMODRST_CPU1, rst_manager_base_addr +
> >   		       SOCFPGA_A10_RSTMGR_MODMPURST);
> > -		memcpy(phys_to_virt(0), &secondary_trampoline, trampoline_size);
> > +		memcpy(phys_to_virt(0), secondary_trampoline, trampoline_size);
> >     		writel(__pa_symbol(secondary_startup),
> >   		       sys_manager_base_addr + (socfpga_cpu1start_addr & 0x00000fff));
> >
>