Re: Understanding Linux addr space, malloc, and heap
From: Alex Bligh - linux-kernel
Date: Fri Oct 21 2005 - 10:38:25 EST
--On 21 October 2005 17:22 +0200 Arjan van de Ven <arjan@xxxxxxxxxxxxx>
wrote:
Ok I meant in the "while adhering to the standard" :)
More precisely, as per the man page:
POSIX.1b says that mprotect can be used only on regions of memory
obtained from mmap(2).
But what is interesting (if anything) is this:
ERRORS
EINVAL addr is not a valid pointer, or not a multiple of
PAGESIZE.
So if he calls mprotect with memory allocated by malloc (which should
fail), why doesn't he get EINVAL? He says it returns 0 (meaning it
succeeded). Which it shouldn't (unless he is stupendously lucky in
malloc's allocation, in which case it should work).
--
Alex Bligh
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