linux-kernel - Re: [PATCH] regset: use vmalloc() for regset_get

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]

Date: Fri, 2 Feb 2024 04:05:03 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: Doug Anderson <dianders@...omium.org>
Cc: Christian Brauner <brauner@...nel.org>,
	Eric Biederman <ebiederm@...ssion.com>, Jan Kara <jack@...e.cz>,
	Kees Cook <keescook@...omium.org>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] regset: use vmalloc() for regset_get_alloc()

On Fri, Feb 02, 2024 at 03:49:25AM +0000, Al Viro wrote:
> On Thu, Feb 01, 2024 at 07:15:48PM -0800, Doug Anderson wrote:
> > >
> > > Well, the next step would be to see which regset it is - if you
> > > see that kind of allocation, print regset->n, regset->size and
> > > regset->core_note_type.
> > 
> > Of course! Here are the big ones:
> > 
> > [   45.875574] DOUG: Allocating 279584 bytes, n=17474, size=16,
> > core_note_type=1029
> 
> 0x405, NT_ARM_SVE
>         [REGSET_SVE] = { /* Scalable Vector Extension */
>                 .core_note_type = NT_ARM_SVE,
>                 .n = DIV_ROUND_UP(SVE_PT_SIZE(SVE_VQ_MAX, SVE_PT_REGS_SVE),
>                                   SVE_VQ_BYTES),
>                 .size = SVE_VQ_BYTES,
> 
> IDGI.  Wasn't SVE up to 32 * 2Kbit, i.e. 8Kbyte max?  Any ARM folks around?
> Sure, I understand that it's variable-sized and we want to allocate enough
> for the worst case, but can we really get about 280Kb there?  Context switches
> would be really unpleasant on such boxen...

FWIW, this apparently intends to be "variable, up to SVE_PT_SIZE(...) bytes";
no idea if SVE_PT_SIZE is the right thing to use here.