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From: "siddhesh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/104964] Wrong *** buffer overflow detected
 ***: terminated - acl
Date: Thu, 17 Mar 2022 11:34:50 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104964

Siddhesh Poyarekar <siddhesh at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |siddhesh at gcc dot=
 gnu.org

--- Comment #5 from Siddhesh Poyarekar <siddhesh at gcc dot gnu.org> ---
I'm not 100% sure if it's invalid code, but I was just about to write that =
it
depends on what the pass ends up seeing.  If earlier passes end up optimizi=
ng
the code such that the objsz pass sees the malloc first (e.g. the reproduce=
r in
pr104961), it ends up with the malloc'd size, otherwise it ends up with the
declared size.

So if it was:

struct bad_struct {=20
  struct g=20=20=20=20=20=20=20=20=20=20
  {=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
    char s_str[1];=20=20
  } i;=20=20=20=20=20=20=20=20=20=20=20=20=20=20
};=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20

and

struct g *i =3D &bad->i;=20=20=20=20=20=20
strcpy (i->s_str, "sparta");

then i tends to get optimized as a MEM_REF of the malloc'd block, letting us
see the extra space.

This needs to be fixed, but then it's possibly a different bug from the one
you're seeing in acl since this affects __bos too, not just __bdos.

(I'm off in a couple of hours btw, returning on Tuesday so I may not get to=
 it
until then)=