Date: Thu, 18 Sep 1997 13:46:45 -0600 (MDT) From: Nate Williams <nate@mt.sri.com> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Nate Williams <nate@mt.sri.com>, Graham Wheeler <gram@cdsec.com>, hackers@freebsd.org Subject: Re: Bug in malloc/free (was: Memory leak in getservbyXXX?) Message-ID: <199709181946.NAA13960@rocky.mt.sri.com> In-Reply-To: <11097.874611676@critter.freebsd.dk> References: <199709181912.NAA13699@rocky.mt.sri.com> <11097.874611676@critter.freebsd.dk>
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> > >[ 'hangs' in malloc due to memory over-write causing circular lists ] > > > >> >> This is about the only way you could get it to loop I think. That means > >> >> that somebody wrote to memory malloc hadn't passed them (ie: your code). > >> > > >> >Yikes, this would be 'Hard to Do', even by design (ie; self-modifying > >> >code). But, stranger things have happened, especially with dealing with > >> >malloc/free. > >> > >> No, all you have to do is to make each allocation have it's own set of > >> pages, munmap them when free is called and never use those pages again. > >> > >> You run out of address space really fast, and it is slow, but it works. > > > >It's slow, but how would it cause malloc to hang? > > It wouldn't, it would detect accesses to free'ed memory. Ahh, I misunderstand what you meant. I thought that you meant that getting PHK-malloc to spin was easy to do with the above, not that detecting it would be easy to do. Nate
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