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SubjectRe: Ulimit Probrems with Linux
On Fri, 21 Aug 1998 brian@nycrc.net wrote:

> >From these tests I can only conclude that if you use malloc to allocate
> buffers larger than 128k the problem will occur consistently. Even if
> ulimit is set to 100 bytes an 8M segment is allocated somewhere. Generally
> speaking, most code does not do this, however, this appears to be a case
> where Apache does. Either there is a significant flaw in my thinking on
> this or a flaw in the way linux is allocating memory. If it's the former,
> well, apologies in advance. If it is the latter, I believe it must be
> addressed since it creates a vulnerability that represents a serious bug.

Right, as you mention mmap is the one doing some of the allocations.

The allocations made by mmap() aren't getting counted against the data
segment (and they aren't really part of it anyway). You will probably
find that the reason some use it and not others has to do with the
heuristic used by mmap() to figure out when it should and shouldn't use
mmap() to allocate memory.

Hmm. I would think a limit on the rss would do something, but it also
doesn't appear to take mmap()ed segments into account even though they are
counted as part of the rss.

ulimit -v does though.


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