From: john.hubbard@gmail.com
To: "H . Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
John Hubbard <jhubbard@nvidia.com>
Subject: [PATCH 0/1] x86/boot: clear some fields explicitly
Date: Wed, 24 Jul 2019 16:15:27 -0700 [thread overview]
Message-ID: <20190724231528.32381-1-jhubbard@nvidia.com> (raw)
From: John Hubbard <jhubbard@nvidia.com>
Hi,
I just ran across this on the latest (well, any -rc1) linux.git, while
working on something else. It generates an ugly multiline warning:
In file included from arch/x86/kernel/head64.c:35:
In function ?sanitize_boot_params?,
inlined from ?copy_bootdata? at arch/x86/kernel/head64.c:391:2:
./arch/x86/include/asm/bootparam_utils.h:40:3: warning:
?memset? offset [197, 448] from the object at ?boot_params? is out
of the bounds of referenced subobject ?ext_ramdisk_image? with type
?unsigned int? at offset 192 [-Warray-bounds]
40 | memset(&boot_params->ext_ramdisk_image, 0,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
41 | (char *)&boot_params->efi_info -
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
42 | (char *)&boot_params->ext_ramdisk_image);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./arch/x86/include/asm/bootparam_utils.h:43:3: warning: ?memset?
offset [493, 497] from the object at ?boot_params? is out of the
bounds of referenced subobject ?kbd_status? with type
?unsigned char? at offset 491 [-Warray-bounds]
43 | memset(&boot_params->kbd_status, 0,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
44 | (char *)&boot_params->hdr -
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~
45 | (char *)&boot_params->kbd_status);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It looks like this hasn't been touched since 2013, so maybe gcc is
just getting more agressive about warnings. Well, we know it is, actually.
Because struct boot_params is __packed__, normal variable
variable assignment will work just as well as a memset here.
Change three u32 fields to be cleared to zero that way, and
just memset the _pad4 field.
This clears up the build warnings for me.
Testing: just did a basic boot test on my x86_64 machine, no problems
seen. Not that that tests much, but it's something.
John Hubbard (1):
x86/boot: clear some fields explicitly
arch/x86/include/asm/bootparam_utils.h | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
--
2.22.0
next reply other threads:[~2019-07-24 23:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-24 23:15 john.hubbard [this message]
2019-07-24 23:15 ` [PATCH 1/1] x86/boot: clear some fields explicitly john.hubbard
2019-07-25 2:12 ` hpa
2019-07-25 6:49 ` John Hubbard
2019-07-25 7:22 ` Thomas Gleixner
2019-07-25 20:33 ` John Hubbard
2019-07-25 21:48 ` Thomas Gleixner
2019-07-25 21:57 ` hpa
2019-07-25 22:03 ` Thomas Gleixner
2019-07-25 22:28 ` H. Peter Anvin
2019-07-25 22:37 ` Thomas Gleixner
2019-07-26 0:36 ` John Hubbard
2019-07-25 22:42 ` John Hubbard
2019-07-26 7:43 ` Thomas Gleixner
2019-07-25 20:38 ` H. Peter Anvin
2019-07-25 20:44 ` John Hubbard
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