Hey folks,

I want to cheat in Linux, that is changing the memory of programs at runtime. Kcheat doesn't build anymore, and I didn't find anything comparable, so I thought of throwing together my own little tool.

I learnt that in order to access /proc/PID/mem, I have to attach first with ptrace. But I'm stumped already at the very beginning. I run the following program under sudo: 

#!/usr/bin/perl
use strict;
use diagnostics;
use Sys::Ptrace qw(ptrace PTRACE_ATTACH);

ptrace PTRACE_ATTACH, 9701;

open my $fh, '<', '/proc/9701/mem' or die "could not open mem for read
+ing: $!";
my $buf;
while (1) {
    my $res = read $fh, $buf, 8*1024;
    die "could not read 8KB from mem: $!" unless defined $res;
    exit if 0 == $res;
    print $buf;
};

[download]

This bombs out with "Input/output error at ptrace.pl line 12.". I don't understand why.

In reply to Accessing proc/memory by Anonymous Monk

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