Messages in this thread | | | Date | Tue, 9 Mar 1999 12:00:04 +0100 (CET) | From | Mikulas Patocka <> | Subject | Re: Simple DoS...out of resources? |
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> > I already thought of it and I think that linux _should_ be more protected > > against such kind of attacks. A simple solution: If there's no swap space, > > the kernel should count which user is taking most memory and kill some his > > processes; not just kill the first process that actually wants memory over > > limit. > > Would you like it if you were that user and the kernel decided to kill > some of your processes ? I'm sure I wouldn't :)
I wouldn't like to be an admin whose daemons die because some luser has a memory leak in his program. :) (note that only browsing with netscape crashed my computer few times because of java applets alocating more & more memory)
Anyway, if the user takes less memory than ((amount of memory+swap)/number of active users), his processes won't get killed. And if he allocates more, he does it at his own risk.
> Also, I thought the process that requests the over-the-limit memory isn't > 'killed'. Surely the memory allocation routine fails. Making the user > program take action.
In many cases allocation fails, but sometimes the process could get SIGBUS or something like it. But it makes no difference - programs die if they can't allocate memory; "better" programs write something like "out of memory, terminating", worse programs work with NULL pointer and crash on SIGSEGV.
Mikulas Patocka
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