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Re: [patch] Error on setenv(..., NULL, ...)

From: Mike Frysinger <vapier at gentoo dot org>
To: Rich Felker <dalias at libc dot org>
Cc: Siddhesh Poyarekar <siddhesh at redhat dot com>, Szabolcs Nagy <szabolcs dot nagy at arm dot com>, Paul Pluzhnikov <ppluzhnikov at google dot com>, GLIBC Devel <libc-alpha at sourceware dot org>
Date: Wed, 11 Mar 2015 15:23:55 -0400
Subject: Re: [patch] Error on setenv(..., NULL, ...)
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References: <CALoOobNSbWUkd_i-L6U0ovbqPYnJY-h=ftX1K61yb19pmJj6aw at mail dot gmail dot com> <20150311163327 dot GV9714 at spoyarek dot pnq dot redhat dot com> <55006F71 dot 6000807 at arm dot com> <20150311164415 dot GW9714 at spoyarek dot pnq dot redhat dot com> <20150311172546 dot GA877 at vapier> <20150311184216 dot GF23507 at brightrain dot aerifal dot cx>

On 11 Mar 2015 14:42, Rich Felker wrote:
> On Wed, Mar 11, 2015 at 01:25:46PM -0400, Mike Frysinger wrote:
> > On 11 Mar 2015 22:14, Siddhesh Poyarekar wrote:
> > > On Wed, Mar 11, 2015 at 04:38:09PM +0000, Szabolcs Nagy wrote:
> > > > no, this just says that NULL argument is undefined behaviour
> > > > 
> > > > this is not a bug in glibc and i don't think any change should be made
> > > 
> > > Fair enough, but if we ever decide to protect ourselves against such
> > > bad access, I'd be in favour of something more conservative like
> > > returning a blank string than returning an error.
> > 
> > if we agree it's undefined behavior, then can't we have fortification turn this 
> > into a build failure ?
> 
> Not a build failure but a runtime trap. UB can't be caught at build
> time because it's only forbidden if the statement that results in UB
> is reached, and reachability is equivalent to the halting problem.

i don't think that nuance matters to fortification.  what i'm talking about 
is when gcc proves a NULL is used.  it already has a nonull warning so it can 
detect this.
-mike

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Follow-Ups:
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Rich Felker

References:
- [patch] Error on setenv(..., NULL, ...)
  - From: Paul Pluzhnikov
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Siddhesh Poyarekar
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Szabolcs Nagy
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Siddhesh Poyarekar
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Mike Frysinger
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Rich Felker

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