From: Eugene Syromiatnikov <esyr@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-m68k@vger.kernel.org
Subject: Re: [GIT PULL] siginfo fix for v4.16-rc5
Date: Sat, 31 Mar 2018 12:56:58 +0200 [thread overview]
Message-ID: <20180331105658.GA4332@asgard.redhat.com> (raw)
In-Reply-To: <87woypy8zc.fsf@xmission.com>
On Tue, Mar 06, 2018 at 01:11:03AM -0600, Eric W. Biederman wrote:
> Linus,
>
> Please pull the siginfo-linus branch from the git tree:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git siginfo-linus
>
> HEAD: f6a015498dcaee72f80283cb7873d88deb07129c signal/x86: Include the field offsets in the build time checks
>
> The kbuild test robot found that I accidentally moved si_pkey when I was
> cleaning up siginfo_t. A short followed by an int with the int having 8
> byte alignment. Sheesh siginfo_t is a weird structure.
>
> I have now corrected it and added build time checks that with a little
> luck will catch any similar future mistakes. The build time checks were
> sufficient for me to verify the bug and to verify my fix. So they are
> at least useful this once.
>
> Eric W. Biederman (2):
> signal: Correct the offset of si_pkey in struct siginfo
Looks like this commit changes layout of the siginfo struct on m68k:
pts/0, esyr@fedora: /tmp % cat si.c
#include <stddef.h>
#include "linux/signal.h"
static const size_t lower_offset = offsetof(struct siginfo, si_lower);
pts/0, esyr@fedora: /tmp % m68k-linux-gnu-gcc -Ikhdr-v4.16-rc1\~159\^2\~20/include -g -c si.c -o si-orig.o
pts/0, esyr@fedora: /tmp % m68k-linux-gnu-gcc -Ikhdr-v4.16-rc3\~17\^2/include -g -c si.c -o si-1.o
pts/0, esyr@fedora: /tmp % m68k-linux-gnu-gcc -Ikhdr-v4.16-rc7-194-g29d9d38/include -g -c si.c -o si-2.o
pts/0, esyr@fedora: /tmp % for i in si-orig.o si-1.o si-2.o; do echo -------- $i; objdump -t -j .rodata $i; objdump -s -j .rodata $i; done
-------- si-orig.o
si-orig.o: file format elf32-big
SYMBOL TABLE:
00000000 l d .rodata 00000000 .rodata
00000000 l O .rodata 00000004 lower_offset
si-orig.o: file format elf32-big
Contents of section .rodata:
0000 00000012 ....
-------- si-1.o
si-1.o: file format elf32-big
SYMBOL TABLE:
00000000 l d .rodata 00000000 .rodata
00000000 l O .rodata 00000004 lower_offset
si-1.o: file format elf32-big
Contents of section .rodata:
0000 00000012 ....
-------- si-2.o
si-2.o: file format elf32-big
SYMBOL TABLE:
00000000 l d .rodata 00000000 .rodata
00000000 l O .rodata 00000004 lower_offset
si-2.o: file format elf32-big
Contents of section .rodata:
0000 00000014 ....
So, the offset of the si_lower field is 20 at the current HEAD and was 18 at
commits v4.16-rc3~17^2 and v4.16-rc1~159^2~20. I believe this is due to
the fact that m68k uses 2-byte default alignment and not 4-byte.
> signal/x86: Include the field offsets in the build time checks
>
> arch/x86/kernel/signal_compat.c | 65 ++++++++++++++++++++++++++++++++++++++
> include/linux/compat.h | 4 +--
> include/uapi/asm-generic/siginfo.h | 4 +--
> 3 files changed, 69 insertions(+), 4 deletions(-)
>
next parent reply other threads:[~2018-03-31 10:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <87woypy8zc.fsf@xmission.com>
2018-03-31 10:56 ` Eugene Syromiatnikov [this message]
2018-04-02 20:17 ` [GIT PULL] siginfo fix for v4.16-rc5 Eric W. Biederman
2018-04-03 7:30 ` Geert Uytterhoeven
2018-04-03 14:27 ` Eric W. Biederman
2018-04-03 15:24 ` Josh Juran
2018-04-03 17:26 ` Andreas Schwab
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