Messages in this thread | | | Date | Mon, 23 Jun 2008 14:53:37 +0100 | From | "Dr. David Alan Gilbert" <> | Subject | mmap_min_addr/SECURITY_DEFAULT_MMAP_MIN_ADDR suggested values |
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Hi, The config help for SECURITY_DEFAULT_MMAP_MIN_ADDR suggests 65536 as a 'reasonable' value for x86 and the original mmap_min_addr patches suggested that 'something like 64k' was a safe value that wouldn't affect most programs.
Where does this 64k value come from? A number of distros seem to have followed this advice and have it set to 64k; but is there really any likely benefit of having it larger than PAGE_SIZE say?
I ask because I have an ancient program that maps stuff at 8k; the general advice of stuff on the net seems to be to set this limit to 0 if people have problems (I'm just lowering it to 4k), but I was thinking perhaps using a lower default value would be more secure since less people would take the easy answer and just turn the feature off altogether.
Dave
-- -----Open up your eyes, open up your mind, open up your code ------- / Dr. David Alan Gilbert | Running GNU/Linux on Alpha,68K| Happy \ \ gro.gilbert @ treblig.org | MIPS,x86,ARM,SPARC,PPC & HPPA | In Hex / \ _________________________|_____ http://www.treblig.org |_______/
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