mmap giving Permission Denied error
anish198519851985 at gmail.com
Sat Sep 21 10:30:27 EDT 2013
On Sep 21, 2013 7:35 PM, "Ravi Teja" <ravi2j at gmail.com> wrote:
> Hello Ratheesh,
> I have intentionally used MAP_FIXED flag as I am interested in mapping to
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 at gmail.com>
>> 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 at 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 =
>>> if(ptr == MAP_FAILED)
>>> perror("Error in mapping\n");
>>> 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.
>>> Ravi Teja
>>> Kernelnewbies mailing list
>>> Kernelnewbies at kernelnewbies.org
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