Re: [PATCH] recipes-devtools: fix segfault in lib32-gcc with "." multilib_dir

[Paul Gortmaker <paul.gortmaker@windriver.com>]

On 14-06-23 11:01 AM, Paul Gortmaker wrote:
> When enabling a lib32-gcc in a 64 bit build, without doing any
> other configuration, the mutilib dir is unspecified, which is
> represented internally in gcc as "." and as such uncovers an
> invalid free on a non-malloc'd pointer, triggered by that code
> path which erroneously checks for equality with "." rather than
> inequality.

It turns out that there is more breakage in the multilib path
handling code than just this, so please hold off on merging
this to oe-core while I work with the gcc folks further here:

https://gcc.gnu.org/ml/gcc-patches/2014-06/msg01842.html

...in order to get a more complete fix.

Thanks,
Paul.
--

> 
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> 
> diff --git a/meta/recipes-devtools/gcc/gcc-4.9.inc b/meta/recipes-devtools/gcc/gcc-4.9.inc
> index 185dbba82200..cbf1355fcbf7 100644
> --- a/meta/recipes-devtools/gcc/gcc-4.9.inc
> +++ b/meta/recipes-devtools/gcc/gcc-4.9.inc
> @@ -66,6 +66,7 @@ SRC_URI = "${GNU_MIRROR}/gcc/gcc-${PV}/gcc-${PV}.tar.bz2 \
>  	   file://0050-Revert-Use-dbx_reg_number-for-spanning-registers.patch \
>             file://0051-eabispe.patch \
>             file://0052-Fix-GCC-targeting-E500-SPE-errors-with-the-_Decimal64-type.patch \
> +           file://0053-gcc-fix-segfault-from-calling-free-on-non-malloc-d-a.patch \
>  	  "
>  SRC_URI[md5sum] = "9709b49ae0e904cbb0a6a1b62853b556"
>  SRC_URI[sha256sum] = "b9b047a97bade9c1c89970bc8e211ff57b7b8998a1730a80a653d329f8ed1257"
> diff --git a/meta/recipes-devtools/gcc/gcc-4.9/0053-gcc-fix-segfault-from-calling-free-on-non-malloc-d-a.patch b/meta/recipes-devtools/gcc/gcc-4.9/0053-gcc-fix-segfault-from-calling-free-on-non-malloc-d-a.patch
> new file mode 100644
> index 000000000000..6cec9d6e1b27
> --- /dev/null
> +++ b/meta/recipes-devtools/gcc/gcc-4.9/0053-gcc-fix-segfault-from-calling-free-on-non-malloc-d-a.patch
> @@ -0,0 +1,46 @@
> +From 5a0d2321f7d4afebb017d0672a04f570ba942f87 Mon Sep 17 00:00:00 2001
> +From: Paul Gortmaker <paul.gortmaker@windriver.com>
> +Date: Fri, 20 Jun 2014 16:41:08 -0400
> +Subject: [PATCH] gcc: fix segfault from calling free on non-malloc'd area
> +
> +We see the following on a 32bit gcc installed on 64 bit host:
> +
> +  Reading symbols from ./i586-pokymllib32-linux-gcc...done.
> +  (gdb) run
> +  Starting program: x86-pokymllib32-linux/lib32-gcc/4.9.0-r0/image/usr/bin/i586-pokymllib32-linux-gcc
> +
> +  Program received signal SIGSEGV, Segmentation fault.
> +  0xf7e957e0 in free () from /lib/i386-linux-gnu/libc.so.6
> +  (gdb) bt
> +  #0  0xf7e957e0 in free () from /lib/i386-linux-gnu/libc.so.6
> +  #1  0x0804b73c in set_multilib_dir () at gcc-4.9.0/gcc/gcc.c:7827
> +  #2  main (argc=1, argv=0xffffd504) at gcc-4.9.0/gcc/gcc.c:6688
> +  (gdb)
> +
> +The problem arises because the check on whether we are using
> +the internal string "." or an allocated one is reversed.
> +We should be calling free() when the string is not equal to
> +the internal "." string.
> +
> +Upstream-Status: Submitted [ https://gcc.gnu.org/ml/gcc-patches/2014-06/msg01778.html ]
> +Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> +---
> + gcc/gcc.c | 2 +-
> + 1 file changed, 1 insertion(+), 1 deletion(-)
> +
> +diff --git a/gcc/gcc.c b/gcc/gcc.c
> +index 6870a840e1b7..a580975a7057 100644
> +--- a/gcc/gcc.c
> ++++ b/gcc/gcc.c
> +@@ -7822,7 +7822,7 @@ set_multilib_dir (void)
> +     }
> + 
> +   if (multilib_dir == NULL && multilib_os_dir != NULL
> +-      && strcmp (multilib_os_dir, ".") == 0)
> ++      && strcmp (multilib_os_dir, ".") != 0)
> +     {
> +       free (CONST_CAST (char *, multilib_os_dir));
> +       multilib_os_dir = NULL;
> +-- 
> +1.9.1
> +
>