[PATCH, PR 57748] Check for out of bounds access, Part 2
Richard Biener
richard.guenther@gmail.com
Tue Sep 24 10:31:00 GMT 2013
On Tue, Sep 24, 2013 at 4:52 AM, Bernd Edlinger
<bernd.edlinger@hotmail.de> wrote:
> Hi,
>
> with the attached patch the read-side of the out of bounds accesses are fixed.
> There is a single new test case pr57748-3.c that is derived from Martin's test case.
> The test case does only test the read access and does not depend on part 1 of the
> patch.
>
> This patch was boot-strapped and regression tested on x86_64-unknown-linux-gnu.
>
> Additionally I generated eCos and an eCos-application (on ARMv5 using packed
> structures) with an arm-eabi cross compiler, and looked for differences in the
> disassembled code with and without this patch, but there were none.
>
> OK for trunk?
Index: gcc/expr.c
===================================================================
--- gcc/expr.c (revision 202778)
+++ gcc/expr.c (working copy)
@@ -9878,7 +9878,7 @@
&& modifier != EXPAND_STACK_PARM
? target : NULL_RTX),
VOIDmode,
- modifier == EXPAND_SUM ? EXPAND_NORMAL : modifier);
+ EXPAND_MEMORY);
/* If the bitfield is volatile, we want to access it in the
field's mode, not the computed mode.
context suggests that we may arrive with EXPAND_STACK_PARM here
which is a correctness modifier (see its docs). But I'm not too familiar
with the details of the various expand modifiers, Eric may be though.
That said, I still believe that fixing the misalign path in expand_assignment
would be better than trying to avoid it. For this testcase the issue is
again that expand_assignment passes the wrong mode/target to the
movmisalign optab.
Richard.
>
> Regards
> Bernd.
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