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: <Z_K5uW2eu7GInRxs@gmail.com>
Date: Sun, 6 Apr 2025 19:28:25 +0200
From: Ingo Molnar <mingo@...nel.org>
To: David Hildenbrand <david@...hat.com>
Cc: 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


* David Hildenbrand <david@...hat.com> wrote:

> We got a late smatch warning and some additional review feedback.
> 
> 	smatch warnings:
> 	mm/memory.c:1428 copy_page_range() error: uninitialized symbol 'pfn'.

> -	if (!(src_vma->vm_flags & VM_PAT))
> +	if (!(src_vma->vm_flags & VM_PAT)) {
> +		*pfn = 0;
>  		return 0;
> +	}

>  static inline int track_pfn_copy(struct vm_area_struct *dst_vma,
>  		struct vm_area_struct *src_vma, unsigned long *pfn)
>  {
> +	*pfn = 0;
>  	return 0;
>  }

That's way too ugly. There's nothing wrong with not touching 'pfn' in 
the error path: in fact it's pretty standard API where output pointers 
may not get set on errors.

If Smatch has a problem with it, Smatch should be fixed, or the false 
positive warning should be worked around by initializing 'pfn' in the 
callers.

Thanks,

	Ingo