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Date: Fri, 30 Mar 2012 22:43:33 +0400
From: Solar Designer <solar@...nwall.com>
To: Jeff Law <law@...hat.com>
Cc: oss-security@...ts.openwall.com
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.
Alexander
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