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Date: Fri, 13 Sep 2013 10:29:00 -0000
From: Marek Polacek <polacek@redhat.com>
To: "Joseph S. Myers" <joseph@codesourcery.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>, Jakub Jelinek <jakub@redhat.com>,        Jason Merrill <jason@redhat.com>
Subject: Re: [PATCH][ubsan] Add VLA bound instrumentation
Message-ID: <20130913095030.GS23899@redhat.com>
References: <20130912122655.GN23899@redhat.com> <Pine.LNX.4.64.1309121546080.5614@digraph.polyomino.org.uk> <Pine.LNX.4.64.1309121555130.5614@digraph.polyomino.org.uk>
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On Thu, Sep 12, 2013 at 04:05:48PM +0000, Joseph S. Myers wrote:
> cause stack overflow that doesn't get detected by the kernel.  So maybe 
> ubsan should imply -fstack-check or similar.

Well, I have a patch for that, but I no longer think that ubsan should
imply -fstack-check, since e.g. 

int
main (void)
{
  int x = -1;
  int b[x - 4];
  /* ... */
  return 0;
}

segfaults at runtime on int b[x - 4]; line when -fstack-check is used
(even without sanitizing), so we wouldn't give proper diagnostics
for stmts following that line...

	Marek