linux-kernel - Re: [PATCH 2.6.26-rc4] Fix nesting error checking in arch/x86/mm/ioremap.c

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] [day] [month] [year] [list]

Message-ID: <20080527080030.GC29246@elte.hu>
Date:	Tue, 27 May 2008 10:00:30 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	mikukkon@....fi
Cc:	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	arjan@...ux.intel.com, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 2.6.26-rc4] Fix nesting error checking in
	arch/x86/mm/ioremap.c

* Mika Kukkonen <mikukkon@...1-m700-lanp.koti> wrote:

>  	unsigned int nesting;
>  
> -	nesting = --early_ioremap_nested;
> -	WARN_ON(nesting < 0);
> +	if (early_ioremap_nested)
> +		nesting = --early_ioremap_nested;
> +	else { 
> +		nesting = 0;
> +		WARN_ON(1);
> +	}

the better fix would be to turn 'nesting' into an int, hm?

Also, instead of forcing nesting to 0, it is better to just return - as 
we cannot do any sane unmap here anymore. (we are unbalanced)

I.e. something like the fix below?

	Ingo

------------------------------>
Subject: ioremap: nesting fix
From: Ingo Molnar <mingo@...e.hu>
Date: Tue May 27 09:56:49 CEST 2008

Mika Kukkonen noticed that the nesting check in early_iounmap() is not 
actually done.

Reported-by: Mika Kukkonen <mikukkon@...1-m700-lanp.koti>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/mm/ioremap.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: linux/arch/x86/mm/ioremap.c
===================================================================
--- linux.orig/arch/x86/mm/ioremap.c
+++ linux/arch/x86/mm/ioremap.c
@@ -602,10 +602,11 @@ void __init early_iounmap(void *addr, un
 	unsigned long offset;
 	unsigned int nrpages;
 	enum fixed_addresses idx;
-	unsigned int nesting;
+	int nesting;
 
 	nesting = --early_ioremap_nested;
-	WARN_ON(nesting < 0);
+	if (WARN_ON(nesting < 0))
+		return;
 
 	if (early_ioremap_debug) {
 		printk(KERN_INFO "early_iounmap(%p, %08lx) [%d]\n", addr,
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/