From: Rich Felker <dalias@libc.org>
To: musl@lists.openwall.com
Subject: Re: Signed integer overflow in __secs_to_tm
Date: Thu, 8 Oct 2015 19:47:27 -0400 [thread overview]
Message-ID: <20151008234727.GD8645@brightrain.aerifal.cx> (raw)
In-Reply-To: <20151007102253.GO10551@port70.net>
On Wed, Oct 07, 2015 at 12:22:53PM +0200, Szabolcs Nagy wrote:
> * Brian Mastenbrook <brian@mastenbrook.net> [2015-10-06 19:09:45 -0500]:
> > __secs_to_tm (used by gmtime_r et al) may invoke undefined
> > behavior due to signed integer overflow in two places. At
> > __secs_to_tm.c:58, 400*qc_cycles may overflow. At
> > __secs_to_tm.c:63, there is a nonsensical comparison between an
> > already overflowed value and INT_MAX or INT_MIN; the compiler will
> > delete this test due to overflow. Here are some example values
> > that provoke the overflow:
> >
>
> i think that computation was supposed to be done
> with long longs and then the comparision is
> sensical and both problems go away.
>
> can you try the attached patch?
It looks good to me. I'm applying it. Thanks!
Rich
prev parent reply other threads:[~2015-10-08 23:47 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-07 0:09 Brian Mastenbrook
2015-10-07 7:24 ` Jens Gustedt
2015-10-07 10:22 ` Szabolcs Nagy
2015-10-08 23:47 ` Rich Felker [this message]
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