Yes, segfault for me too after i changed ADDR preprocessor directive to the VMA address from objdump, as the instruction says. I'm on Ubuntu Linux 13.10 x64.
Ubuntu adds a security feature that provides a read-only relocation table area in the final ELF. To be able to run the examples in ubuntu, add this in the command line when compiling
ok, now it compiles, thanks for that. However, I'm getting an incomplete response "<h1>hello world</h1" without the trailing closing angled bracket. And when I try to run final.c after setting the FUNCTION_ADDR and ADDR as per your tutorial, I get some stray HTTP/1.0 200 and Content-type text/html being displayed on stdout as I start the program final.c (compiled to a.out by default)
Ah, you have found a bug in my code (I made an error in computing the string length, and didn't notice it because it displayed fine on Chrome). I have fixed my code in git and the blog post.
As for the stray output displayed on the stdout: it is to be expected. The %n format outputs the numbers of character that is written by printf, so it must have written something to the stdout.
Ah! that explains so much (and also why i've wasted a whole hour figuring out why what I observed was happening) I'm a CLI curl guy, rather than relying on these browsers which randomly would add a 0x0d 0x0a to my form submissions, for example. I also noticed that compiling (assembling-linking) the .S to execute it would not print anything (just hang there like a normal webserver), but I was getting stuff written to stdout with the final.c/webserver.c version using its shellcode.
