Date: Wed, 22 May 2013 19:56:12 -0400 (EDT)
From: Vince Weaver <vincent.weaver@maine.edu>
To: Vince Weaver <vincent.weaver@maine.edu>
cc: linux-kernel@vger.kernel.org, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
        trinity@vger.kernel.org
Subject: Re: OOPS in perf_mmap_close()
In-Reply-To: <alpine.DEB.2.10.1305221523420.9944@vincent-weaver-1.um.maine.edu>
Message-ID: <alpine.DEB.2.10.1305221953370.11450@vincent-weaver-1.um.maine.edu>
References: <alpine.DEB.2.10.1305221523420.9944@vincent-weaver-1.um.maine.edu>
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> In any case while letting it run I got the following OOPS on 
> Linux 3.10-rc2

Included below is test code (based on the fuzzer output) that reliably 
OOPSes my core2 machine.  It's a bit long, but I'm remote from the 
machine now so I can't refine it (as the code locked up the machine the 
last time I tested).


/* perf_mmap_close_bug.c */
/* By Vince Weaver <vincent.weaver at maine.edu>                             */
/* compile with "gcc -O2 -Wall -o perf_mmap_close_bug perf_mmap_close_bug.c  */
/* This will reliably OOPS my core2 Linux 3.10-rc2 machine                   */

#include <stdio.h>
#include <linux/perf_event.h>
#include <sys/mman.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>

int perf_event_open(struct perf_event_attr *hw_event_uptr,
                    pid_t pid, int cpu, int group_fd, unsigned long flags) {

   return syscall(__NR_perf_event_open,hw_event_uptr, pid, cpu,
                  group_fd, flags);
}


int main(int argc, char **argv) {

	struct perf_event_attr pe1,pe2;
	int fd1,fd2;

	memset(&pe1,0,sizeof(struct perf_event_attr));
	memset(&pe2,0,sizeof(struct perf_event_attr));

	pe1.type=0;
	pe1.size=0x60;
	pe1.config=3;
	pe1.sample_type=0x4f0;
	pe1.read_format=5;
	pe1.exclude_kernel=1;
	pe1.bp_type=1;
	pe1.config1=0x1d469257;
	pe1.config2=2;

	fd1=perf_event_open(&pe1,0,0,-1,3);
	if (fd1<0) {
		fprintf(stderr,"Error opening fd1 %s\n",strerror(errno));
		exit(1);
	}

	mmap(NULL, 69632, PROT_READ|PROT_WRITE, MAP_SHARED, fd1, 0);

	ioctl(fd1,PERF_EVENT_IOC_RESET,0);

	pe2.type=1;
	pe2.size=0x60;
	pe2.config=2;
	pe2.read_format=3;
	pe2.exclusive=1;
	pe2.exclude_user=1;
	pe2.mmap=1;
	pe2.inherit_stat=1;
	pe2.enable_on_exec=1;
	pe2.task=1;
	pe2.watermark=1;
	pe2.precise_ip=2;
	pe2.sample_id_all=1;
	pe2.exclude_guest=1;
	pe2.wakeup_events=1500395763;

	fd2=perf_event_open(&pe2,0,0,fd1,3);

	fd1=perf_event_open(&pe1,0,0,-1,3);
	if (fd2<0) {
		fprintf(stderr,"Error opening fd2 %s\n",strerror(errno));
		exit(1);
	}

	mmap(NULL, 69632, PROT_READ|PROT_WRITE, MAP_SHARED, fd2, 0);

	ioctl(fd1,PERF_EVENT_IOC_ENABLE,0);

	ioctl(fd2,PERF_EVENT_IOC_ENABLE,0);

   	close(fd2);

	return 0;
}
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