Date: Sun, 15 Apr 2018 13:52:10 +0200 From: ardi <ardillasdelmonte@...il.com> To: musl@...ts.openwall.com Subject: Re: tcmalloc compatibility On Tue, Apr 10, 2018 at 11:17 PM, Szabolcs Nagy <nsz@...t70.net> wrote: > > then the wrappers with dlsym(RTLD_NEXT,sym) would not work. > (malloc checkers, valgrind, sanitizers etc all do it) I've been using ElectricFence, as my only memory debugger since 1996 or so; mostly with the libc of commercial Unices, but also with glibc in Linux, and with the OSX libc. I never considered I could run into the issues commented in this thread, and in fact I never faced these issues and it always worked as expected (however, I must admit I only use multithreading for accelerating clearly isolated math-intensive loops that don't call malloc-related functions from inside the loop). Said this, when I'm linking with ElectricFence, my brain has the "hack mode flag" ON (I mean, I always had the feeling that I'm working with a temporary hack that can fail whenever my link line contains -lefence , and I'm aware that things can go wrong --I didn't consider thread safety, but anyway I know ElectricFence can fail if the OS syscalls that allocate protected memory at buffer ends change their behaviour in newer versions, or if there's some OS/CPU-dependent subtlety with alignment, etc...) I've not tried to use ElectricFence with musl yet... but reading this, can I suppose it won't work? Is there any "hack mode ON" procedure (yet easy) that would allow to use ElectricFence (assuming non-threaded code, which is always my case). I agree with your commitment to correctness, and I'm not asking for a safe and guaranteed implementation of function interposition, just that sometimes I need to break my binaries to make them crash hard as soon as pointer accesses a byte it shouldn't access. Cheers, ardi
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