Re: Understanding Linux addr space, malloc, and heap

[Paulo Marques]

Vincent W. Freeh wrote:
> First, thanks for all the help and attention.  I am learning much.
>
> I think the focus of this discussion should be on mprotect.  I 
> understand that spec says it only works on mmap'd memory.  So does 
> malloc use mmap?  If not why does it work at all?
>
> Probably the most problematic issue, tho, is why does mprotect return 0 
> even though it failed to change permissions on the 66th page?

Do you have code that shows this?

I tried to change the example in the mprotect man page to loop N times 
(N given on the command line) malloc'ing and mprotect'ing N pages and 
then accessing the N'th page and it always gave SIGSEGV, for any N from 
1 to 100.

--
Paulo Marques - www.grupopie.com

The rule is perfect: in all matters of opinion our
adversaries are insane.
Mark Twain
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