Date: Sat, 15 Apr 2017 12:13:28 +0200 From: Andreas Lausch-Waas <andreas@...usch.at> To: oss-security@...ts.openwall.com Subject: Re: alloca in inline functions can be dangerous On 2017-04-10 16:55, Leandro Pereira wrote: > On Mon, Apr 10, 2017 at 7:36 AM, Jason A. Donenfeld <Jason@...c4.com> wrote: >> I'm interested if anybody else has encountered this behavior or has any >> thoughts about it. > Yes, and I usually mark those functions with __attribute__((noinline)) > to avoid precisely this kind of behavior. > This (VLAs in loops or inlines filling the stack) would be a gcc bug: "Jumping or breaking out of the scope of the array name deallocates the storage. Jumping into the scope is not allowed; you get an error message for it.". See https://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html At least GCC 6.3.1 does not call alloca for VLAs. -- Andreas
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