On 2015/2/13 18:44, Catalin Marinas wrote: > 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. Sorry for confuse. I was considering if the pointer in sival_ptr is greater than 32bit in 64bit application. But it seems that it is not relative to my issue: We only talk about the 32bit application here. >>> 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: Agree. I was thinking if it is not very clear that app write to si_ptr in userspace while kernel only read/write si_int. regards bamvor >>>>> 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) > -- 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
