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Date: Fri, 30 Mar 2012 22:43:33 +0400
From: Solar Designer <>
To: Jeff Law <>
Subject: Re: glibc crypt(3), crypt_r(3), PHP crypt() may use alloca()

On Fri, Mar 30, 2012 at 12:27:31PM -0600, Jeff Law wrote:
> I think the right way to handle the return value is to return NULL for 
> these cases.  It's posix complaint and the glibc crypt routines already 
> return NULL for exceptional conditions.

Do you realize that plenty of services that use crypt() - likely the
majority of them, even - don't handle NULL returns, so they will
segfault when these conditions are triggered?  (That's assuming there
is no way for an attacker to get something mmap()'ed at NULL in the
service.)  I think the NULL returns got into POSIX starting with 2001;
if so, anything written earlier than that legitimately does not handle
NULL returns (and indeed a lot of newer code also does not).

I have to admit that DragonFly BSD also recently went with NULL returns,
and I failed to convince them to do otherwise.

NetBSD went with my suggestion of "*0" / "*1", though.


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