linux-kernel - Re: [PATCH 2/4] sparc: fix accurate exception reporting in copy_{from_to}

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <dd35a213ce2f42a97d791415b594396466da5b14.camel@physik.fu-berlin.de>
Date: Thu, 28 Aug 2025 17:53:19 +0200
From: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
To: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>, 
	linux-kernel@...r.kernel.org
Cc: sparclinux@...r.kernel.org, Andreas Larsson <andreas@...sler.com>, 
 Anthony Yznaga <anthony.yznaga@...cle.com>
Subject: Re: [PATCH 2/4] sparc: fix accurate exception reporting in
 copy_{from_to}_user for UltraSPARC III

Hello,

On Tue, 2025-08-26 at 18:03 +0200, Michael Karcher wrote:
> Based on a finding by Anthony Yznaga that the UltraSPARC III copy_from_user
> returns invalid values breaking other parts of the kernel in case of a
> fault, while the generic implementation is correct.
> 
> Fixes: ee841d0aff64 ("sparc64: Convert U3copy_{from,to}_user to accurate exception reporting.")
> Signed-off-by: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>
> ---
>  arch/sparc/lib/U3memcpy.S | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/sparc/lib/U3memcpy.S b/arch/sparc/lib/U3memcpy.S
> index 9248d59c734c..bace3a18f836 100644
> --- a/arch/sparc/lib/U3memcpy.S
> +++ b/arch/sparc/lib/U3memcpy.S
> @@ -267,6 +267,7 @@ FUNC_NAME:	/* %o0=dst, %o1=src, %o2=len */
>  	faligndata	%f10, %f12, %f26
>  	EX_LD_FP(LOAD(ldd, %o1 + 0x040, %f0), U3_retl_o2)
>  
> +	and		%o2, 0x3f, %o2
>  	subcc		GLOBAL_SPARE, 0x80, GLOBAL_SPARE
>  	add		%o1, 0x40, %o1
>  	bgu,pt		%XCC, 1f
> @@ -336,7 +337,6 @@ FUNC_NAME:	/* %o0=dst, %o1=src, %o2=len */
>  	 * Also notice how this code is careful not to perform a
>  	 * load past the end of the src buffer.
>  	 */
> -	and		%o2, 0x3f, %o2
>  	andcc		%o2, 0x38, %g2
>  	be,pn		%XCC, 2f
>  	 subcc		%g2, 0x8, %g2

After further testing, it turned out that the previously observed crash was
related to my build environment. I can confirm that with the patch applied,
the previously observed memory corruptions on UltraSPARC III are fixed.

Tested-by: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913