Hello all, I have successfully acessed(read and write) to 0x00000000(NULL) address. I had to make certain changes in .config file and recompile it. Thank you all. Regards Ravi Teja On Sat, Sep 21, 2013 at 8:00 PM, anish singh <anish198519851985@gmail.com>wrote:
On Sep 21, 2013 7:35 PM, "Ravi Teja" <ravi2j@gmail.com> wrote:
Hello Ratheesh,
I have intentionally used MAP_FIXED flag as I am interested in mapping
to 0x00000000. AFAICS in linux generally mapping to null address is not allowed as this decision helps in debugging null dereference errors.
Even after setting the mmap_min_addr in /proc/sys/vm to 0 (which was
previously 4096), I am getting this error.
Is there anything wrong that I am doing?
On Sat, Sep 21, 2013 at 7:17 PM, ratheesh kannoth <
ratheesh.ksz@gmail.com> wrote:
MAP_FIXED could be trying to get a map from 0.
Pls remove this flag and try.
On Sat, Sep 21, 2013 at 6:55 PM, Ravi Teja <ravi2j@gmail.com> wrote:
Hello all,
I tried mmap'ing to address zero after setting
/proc/sys/vm/mmap_min_addr to 0, but mmap is giving Permission Denied error.
My C code is as below -
#include <stdio.h> #include <stdlib.h> #include <sys/mman.h>
int main(void) { int *ptr = NULL; ptr =
mmap(0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,-1,0);
if(ptr == MAP_FAILED) { perror("Error in mapping\n"); exit(1); } printf("After mmap\n"); *ptr = 16; printf("Contents of address 0x%x is :: %d\n",ptr,*ptr); return 0; }
Am I doing anything wrong here?
Thank you in advance.
Regards, Ravi Teja
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