linux-kernel - Re: [PATCH] MIPS: Fix IRQ tracing when call handle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200525084234.GA5057@alpha.franken.de>
Date:   Mon, 25 May 2020 10:42:34 +0200
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     YuanJunQing <yuanjunqing66@....com>
Cc:     paulburton@...nel.org, chenhc@...ote.com,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        liulichao@...ngson.cn
Subject: Re: [PATCH] MIPS: Fix IRQ tracing when call handle_fpe()

On Mon, May 25, 2020 at 11:31:23AM +0800, YuanJunQing wrote:
>  Register "a1" is unsaved in this function,
>  when CONFIG_TRACE_IRQFLAGS is enabled,
>  the TRACE_IRQS_OFF macro will call trace_hardirqs_off(),
>  and this may change register "a1".
>  The variment of register "a1" may send SIGFPE signal
>  to task when call do_fpe(),and this may kill the task.
> 
> Signed-off-by: YuanJunQing <yuanjunqing66@....com>
> ---
>  arch/mips/kernel/genex.S | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
> index 8236fb291e3f..956a76429773 100644
> --- a/arch/mips/kernel/genex.S
> +++ b/arch/mips/kernel/genex.S
> @@ -480,16 +480,18 @@ NESTED(nmi_handler, PT_SIZE, sp)
>  	/* gas fails to assemble cfc1 for some archs (octeon).*/ \
>  	.set	mips1
>  	SET_HARDFLOAT
> -	cfc1	a1, fcr31
> +	cfc1	s0, fcr31
>  	.set	pop
>  	CLI
>  	TRACE_IRQS_OFF
> +	move    a1,s0
>  	.endm

do we realy need to read fcr31 that early ? Wouldn't it work to
just move the cfc1 below TRACE_IRQS_OFF ?

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]