On Fri, Oct 7, 2011 at 4:13 AM, Vaibhav Jain <vjoss197@xxxxxxxxx> wrote:
Hi Vaibhav,On Thu, Oct 6, 2011 at 11:28 AM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote:
Hi...
Probably this could also due to mmap NULL dereferencing protection (at
On Thu, Oct 6, 2011 at 02:34, Vaibhav Jain <vjoss197@xxxxxxxxx> wrote:
> Hi,
>
> I am trying to run a program that scans memory from a given physical address
> using /dev/mem.
> It uses mmap to map physical address from /dev/mem. So to start with I used
> /proc/iomem to look up the
> physical memory mapping and found the address 00010000 to be the starting
> address for System ram. But whenever I
> provide this address to the program it throws an error of "Operation not
> permitted".
least that's how I name it :) )
By default, the lowest 65536 byte (10000 in hex) is protected from
mapping etc. It practically render such null dererefencing useless.
--
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com
Hi,I tried the same with other addresses (greater than 0x10000 ) also but it is throwing the same error.Is there a way to get over this ?ThanksVaibhav Jain
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This is how it can be done. Refer link http://www.theknotter.net/system-memory-dumps-on-linux/
I have attached the modified code which disables the socket creation part and dumps the output in a file.
Regards,
Rohan Puri
/*
* Copyright (c) 2010, digital <digital [at] theknotter [dot] net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#define _GNU_SOURCE 1
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/mman.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#define MEM_FILE "/dev/mem"
#define IOM_FILE "/proc/iomem"
int main(/*int argc, char *argv[]*/)
{
FILE *map_file;
int mem_fd, sock;
long unsigned int r0, r1;
long unsigned int count;
long unsigned int chunk;
char *ptr, *mem;
size_t n;
int rohan;
// struct sockaddr_in addr;
/* if (argc != 3) {
printf("USAGE: %s <ip> <port>\n", argv[0]);
return -1;
}
*/
if (!(map_file = fopen(IOM_FILE, "r"))) {
perror("fopen");
return -1;
}
if ((mem_fd = open(MEM_FILE, O_RDONLY)) < 0) {
perror("fopen");
return -1;
}
if ((rohan = open("./rohan.txt", O_WRONLY | O_CREAT)) < 0) {
perror("fopen");
return -1;
}
/* if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) {
perror("socket");
return -1;
}
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = inet_addr(argv[1]);
addr.sin_port = htons(atoi(argv[2]));
if (connect(sock, (struct sockaddr*) &addr, sizeof(addr)) < 0) {
perror("connect");
return -1;
}
*/
for (ptr = NULL; getline(&ptr, &n, map_file) > 0;) {
if (ptr[0] == ' ' || !strstr(ptr, "System RAM"))
continue;
if (sscanf(ptr, "%lx-%lx", &r0, &r1) != 2) {
return -1;
}
if (r1 % 4096)
r1 = (r1 - (r1 % 4096)) + 4096;
count = r1 - r0;
for (chunk = count / 4096; chunk > 0; chunk--) {
mem = mmap(NULL, 4096, PROT_READ, MAP_PRIVATE,
mem_fd, r0 + (count - (chunk * 4096)));
if (mem == (void*) -1) {
char zeroed[4096] = { 0 };
if (write(rohan , zeroed, 4096) != 4096) {
perror("write");
return -1;
}
continue;
}
if (write(rohan , mem, 4096) != 4096) {
perror("write");
return -1;
}
munmap(mem, 4096);
}
}
free(ptr);
close(mem_fd);
fclose(map_file);
close(sock);
return 0;
}
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