linux-kernel - Re: [PATCH v1] x86/mm/pat: (un)track_pfn

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: <4961949a-75db-4071-a478-fdc543c1dd28@stanley.mountain>
Date: Mon, 7 Apr 2025 21:33:54 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: David Hildenbrand <david@...hat.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, x86@...nel.org,
	kernel test robot <lkp@...el.com>,
	Dan Carpenter <error27@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Rik van Riel <riel@...riel.com>, "H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v1] x86/mm/pat: (un)track_pfn_copy() fix + improvements

On Mon, Apr 07, 2025 at 06:50:43PM +0200, Ingo Molnar wrote:
> > diff --git a/mm/memory.c b/mm/memory.c
> > index 2d8c265fc7d60..1a35165622e1c 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -1361,7 +1361,7 @@ copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
> >         struct mm_struct *dst_mm = dst_vma->vm_mm;
> >         struct mm_struct *src_mm = src_vma->vm_mm;
> >         struct mmu_notifier_range range;
> > -       unsigned long next, pfn;
> > +       unsigned long next, pfn = 0;
> 
> Ack.
> 
> I hate it how uninitialized variables are even a thing in C, and why
> there's no compiler switch to turn it off for the kernel. (At least for
> non-struct variables. Even for structs I would zero-initialize and
> *maybe* allow a non-initialized opt-in for cases where it matters. It
> matters in very few cases in praxis. And don't get me started about the
> stupidity that is to not initialize holes in struct members ...)

Everyone sane uses CONFIG_INIT_STACK_ALL_ZERO these days.

regards,
dan carpenter