On Fri, Feb 13, 2015 at 04:00:43PM +0800, Bamvor Jian Zhang wrote:
On 2015/2/11 23:40, Catalin Marinas wrote:
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On Wed, Feb 11, 2015 at 07:22:08PM +0800, Bamvor Jian Zhang wrote:
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On 2015/2/10 20:27, Catalin Marinas wrote:
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On Tue, Feb 10, 2015 at 10:10:11AM +0000, Zhang Jian(Bamvor) wrote:
...
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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.
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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.
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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:
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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