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(-) >
