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Re: [PATCH] gdb: fix sparc memcpy fortify error
- From: Mark Kettenis <mark dot kettenis at xs4all dot nl>
- To: vapier at gentoo dot org
- Cc: gdb-patches at sourceware dot org
- Date: Fri, 19 Mar 2010 10:25:49 +0100 (CET)
- Subject: Re: [PATCH] gdb: fix sparc memcpy fortify error
- References: <1268964549-30380-1-git-send-email-vapier@gentoo.org>
> From: Mike Frysinger <vapier@gentoo.org>
> Date: Thu, 18 Mar 2010 22:09:09 -0400
>
> Building on an x86_64-linux system with --enable-targets=all fails on the
> sparc code with a fortify error:
>
> cc1: warnings being treated as errors
> In file included from /usr/include/string.h:640,
> from gnulib/string.h:23,
> from ../../gdb/gdb_string.h:25,
> from ../../gdb/vec.h:25,
> from ../../gdb/memattr.h:24,
> from ../../gdb/target.h:60,
> from ../../gdb/exec.h:23,
> from ../../gdb/gdbcore.h:31,
> from ../../gdb/sparc-tdep.c:29:
> In function 'memcpy',
> inlined from 'sparc32_store_return_value' at ../../gdb/sparc-tdep.c:1112,
> inlined from 'sparc32_return_value' at ../../gdb/sparc-tdep.c:1170:
> /usr/include/bits/string3.h:52: error: call to __builtin___memcpy_chk will
> always overflow destination buffer
> make: *** [sparc-tdep.o] Error 1
That's a false positive I'm afraid. I agree that it isn't trivial to
see that there is no buffer overflow here. Unfortunately your
solution is a bit problematic:
> 2010-03-18 Mike Frysinger <vapier@gentoo.org>
>
> * gdb/sparc-tdep.c (sparc32_store_return_value): Declare the length
> of buf using the "len" variable.
>
> gdb/sparc-tdep.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/gdb/sparc-tdep.c b/gdb/sparc-tdep.c
> index f129a55..ea0cdd2 100644
> --- a/gdb/sparc-tdep.c
> +++ b/gdb/sparc-tdep.c
> @@ -1101,7 +1101,7 @@ sparc32_store_return_value (struct type *type, struct regcache *regcache,
> const gdb_byte *valbuf)
> {
> int len = TYPE_LENGTH (type);
> - gdb_byte buf[8];
> + gdb_byte buf[max(len, 8)];
Sorry, but variable sized arrays aren't C90.
Does it help if you replace
> gdb_assert (!(sparc_floating_p (type) && len == 16));
with
gdb_assert (len <= 8);
?