On Fri, Feb 13, 2015 at 04:00:43PM +0800, Bamvor Jian Zhang wrote: > On 2015/2/11 23:40, Catalin Marinas wrote: > > On Wed, Feb 11, 2015 at 07:22:08PM +0800, Bamvor Jian Zhang wrote: > >> On 2015/2/10 20:27, Catalin Marinas wrote: > >>> On Tue, Feb 10, 2015 at 10:10:11AM +0000, Zhang Jian(Bamvor) wrote: > ... > > The native sigval_t is also a union but on 64-bit big endian, the > > sival_int overlaps with the most significant 32-bit of the sival_ptr. > > So reading sival_int would always be 0. When the compat siginfo is > > copied to user, arm64 reads the native sival_ptr (si_ptr) and converts > > it to the compat one, getting the correct 32-bit value. However, other > > architectures access sival_int (si_int) instead which breaks with your > > get_compat_sigevent() changes. > > > >>> I think the correct fix is in the arm64 code: > >> > >> The following code could fix my issue. > > > > Without any parts of your patch? > > Yes. As you mentioned above, sival_int overlaps the most significant 32bit > of the sival_ptr, it seems that your patch is right if sival_ptr is less than > 32bit. I don't follow you here. sival_ptr is greater than 32-bit on a 64-bit kernel. > > I think that's correct fix since in the SIGEV_THREAD mq_notify case, we > > would not deliver a signal as notification, so the sival_int value is > > irrelevant (it would be 0 for big-endian compat tasks because of the > > sigval_t union on 64-bit). > > > > Your patch would work as well but you have to change all the other > > architectures to use si_ptr when copying to a compat siginfo. > > Yeah, it seems that my patch is useful only if the sival_ptr is bigger > than 32bit. It need the similar changes with following catalin's patch > in the following 64bit architecture: > > x86: arch/x86/ia32/ia32_signal.c That's a little endian architecture and the use of ptr_to_compat() looks fine to me. > tile, s390: arch/xxx/kernel/compat_signal.c s390 uses si_int already, as in my proposed arm64 patch. tile seems to be bi-endian, though I couldn't see a Kconfig option, nor something defining __BIG_ENDIAN__ in headers or Makefile. I guess it's coming from the compiler directly. Anyway, on big endian tile, I we have the same issue as on big endian arm64. > parisc, sparc, mips: arch/xxx/kernel/signal32.c paris, sparc and mips all use si_int instead of si_ptr, so that's fine. > powerpc: arch/xxx/kernel/signal_32.c Same for powerpc, it uses si_int instead of si_ptr. > cc these maintainers for input. I think it's only tile that needs fixing for big endian, something like the arm64 patch below: > >>> diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c > >>> index e299de396e9b..32601939a3c8 100644 > >>> --- a/arch/arm64/kernel/signal32.c > >>> +++ b/arch/arm64/kernel/signal32.c > >>> @@ -154,8 +154,7 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from) > >>> case __SI_TIMER: > >>> err |= __put_user(from->si_tid, &to->si_tid); > >>> err |= __put_user(from->si_overrun, &to->si_overrun); > >>> - err |= __put_user((compat_uptr_t)(unsigned long)from->si_ptr, > >>> - &to->si_ptr); > >>> + err |= __put_user(from->si_int, &to->si_int); > >>> break; > >>> case __SI_POLL: > >>> err |= __put_user(from->si_band, &to->si_band); > >>> @@ -184,7 +183,7 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from) > >>> case __SI_MESGQ: /* But this is */ > >>> err |= __put_user(from->si_pid, &to->si_pid); > >>> err |= __put_user(from->si_uid, &to->si_uid); > >>> - err |= __put_user((compat_uptr_t)(unsigned long)from->si_ptr, &to->si_ptr); > >>> + err |= __put_user(from->si_int, &to->si_int); > >>> break; > >>> case __SI_SYS: > >>> err |= __put_user((compat_uptr_t)(unsigned long) -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
