[Y2038] [PATCH] aio: Wire up compat_sys_io_pgetevents_time64 for x86
The LTP test io_pgetevents02 fails in 32bit compat mode because an
nr_max of -1 appears to be treated as a large positive integer. This
causes pgetevents_time64 to return an event. The test expects the call
to fail and errno to be set to EINVAL.
Using the compat syscall fixes the issue.
Fixes: 7a35397f8c06 ("io_pgetevents: use __kernel_timespec")
Signed-off-by: Richard Palethorpe
---
arch/x86/entry/syscalls/syscall_32.tbl | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl
b/arch/x86/entry/syscalls/syscall_32.tbl
index 960a021d543e..0985d868 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -420,7 +420,7 @@
412i386utimensat_time64sys_utimensat
413i386pselect6_time64 sys_pselect6
compat_sys_pselect6_time64
414i386ppoll_time64sys_ppoll
compat_sys_ppoll_time64
-416i386io_pgetevents_time64sys_io_pgetevents
+416i386io_pgetevents_time64sys_io_pgetevents
compat_sys_io_pgetevents_time64
417i386recvmmsg_time64 sys_recvmmsg
compat_sys_recvmmsg_time64
418i386mq_timedsend_time64 sys_mq_timedsend
419i386mq_timedreceive_time64 sys_mq_timedreceive
--
2.31.1
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Re: [Y2038] [PATCH] aio: Wire up compat_sys_io_pgetevents_time64 for x86
Richard Palethorpe writes:
> Hello Arnd,
>
> Arnd Bergmann writes:
>
>> On Tue, Sep 21, 2021 at 3:01 PM Richard Palethorpe
>> wrote:
>>>
>>> The LTP test io_pgetevents02 fails in 32bit compat mode because an
>>> nr_max of -1 appears to be treated as a large positive integer. This
>>> causes pgetevents_time64 to return an event. The test expects the call
>>> to fail and errno to be set to EINVAL.
>>>
>>> Using the compat syscall fixes the issue.
>>>
>>> Fixes: 7a35397f8c06 ("io_pgetevents: use __kernel_timespec")
>>> Signed-off-by: Richard Palethorpe
>>
>> Thanks a lot for finding this, indeed there is definitely a mistake that
>> this function is defined and not used, but I don't yet see how it would
>> get to the specific failure you report.
>>
>> Between the two implementations, I can see a difference in the
>> handling of the signal mask, but that should only affect architectures
>> with incompatible compat_sigset_t, i.e. big-endian or
>> _COMPAT_NSIG_WORDS!=_NSIG_WORDS, and the latter is
>> never true for currently supported architectures. On x86, there is
>> no difference in the sigset at all.
>>
>> The negative 'nr' and 'min_nr' arguments that you list as causing
>> the problem /should/ be converted by the magic
>> SYSCALL_DEFINE6() definition. If this is currently broken, I would
>> expect other syscalls to be affected as well.
>
> That is what I thought, but I couldn't think of another explanation for
> it.
>
>>
>> Have you tried reproducing this on non-x86 architectures? If I
>> misremembered how the compat conversion in SYSCALL_DEFINE6()
>> works, then all architectures that support CONFIG_COMPAT have
>> to be fixed.
>>
>> Arnd
>
> No, but I suppose I can try it on ARM or PowerPC. I suppose printing the
> arguments would be a good idea too.
It appears it really is failing to sign extend the s32 to s64. I added
the following printks
modified fs/aio.c
@@ -2054,6 +2054,7 @@ static long do_io_getevents(aio_context_t ctx_id,
long ret = -EINVAL;
if (likely(ioctx)) {
+ printk("comparing %ld <= %ld\n", min_nr, nr);
if (likely(min_nr <= nr && min_nr >= 0))
ret = read_events(ioctx, min_nr, nr, events, until);
percpu_ref_put(&ioctx->users);
@@ -2114,6 +2115,8 @@ SYSCALL_DEFINE6(io_pgetevents,
bool interrupted;
int ret;
+ printk("io_pgetevents(%lx, %ld, %ld, ...)\n", ctx_id, min_nr, nr);
+
if (timeout && unlikely(get_timespec64(&ts, timeout)))
return -EFAULT;
Then the output is:
[ 11.252268] io_pgetevents(f7f19000, 4294967295, 1, ...)
[ 11.252401] comparing 4294967295 <= 1
io_pgetevents02.c:114: TPASS: invalid min_nr: io_pgetevents() failed as
expected: EINVAL (22)
[ 11.252610] io_pgetevents(f7f19000, 1, 4294967295, ...)
[ 11.252748] comparing 1 <= 4294967295
io_pgetevents02.c:103: TFAIL: invalid max_nr: io_pgetevents() passed
unexpectedly
--
Thank you,
Richard.
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Re: [Y2038] [PATCH] aio: Wire up compat_sys_io_pgetevents_time64 for x86
Hello Arnd,
Arnd Bergmann writes:
> On Tue, Sep 21, 2021 at 3:01 PM Richard Palethorpe
> wrote:
>>
>> The LTP test io_pgetevents02 fails in 32bit compat mode because an
>> nr_max of -1 appears to be treated as a large positive integer. This
>> causes pgetevents_time64 to return an event. The test expects the call
>> to fail and errno to be set to EINVAL.
>>
>> Using the compat syscall fixes the issue.
>>
>> Fixes: 7a35397f8c06 ("io_pgetevents: use __kernel_timespec")
>> Signed-off-by: Richard Palethorpe
>
> Thanks a lot for finding this, indeed there is definitely a mistake that
> this function is defined and not used, but I don't yet see how it would
> get to the specific failure you report.
>
> Between the two implementations, I can see a difference in the
> handling of the signal mask, but that should only affect architectures
> with incompatible compat_sigset_t, i.e. big-endian or
> _COMPAT_NSIG_WORDS!=_NSIG_WORDS, and the latter is
> never true for currently supported architectures. On x86, there is
> no difference in the sigset at all.
>
> The negative 'nr' and 'min_nr' arguments that you list as causing
> the problem /should/ be converted by the magic
> SYSCALL_DEFINE6() definition. If this is currently broken, I would
> expect other syscalls to be affected as well.
That is what I thought, but I couldn't think of another explanation for
it.
>
> Have you tried reproducing this on non-x86 architectures? If I
> misremembered how the compat conversion in SYSCALL_DEFINE6()
> works, then all architectures that support CONFIG_COMPAT have
> to be fixed.
>
> Arnd
No, but I suppose I can try it on ARM or PowerPC. I suppose printing the
arguments would be a good idea too.
--
Thank you,
Richard.
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Re: [Y2038] [PATCH] aio: Wire up compat_sys_io_pgetevents_time64 for x86
On Tue, Sep 21, 2021 at 3:01 PM Richard Palethorpe wrote:
>
> The LTP test io_pgetevents02 fails in 32bit compat mode because an
> nr_max of -1 appears to be treated as a large positive integer. This
> causes pgetevents_time64 to return an event. The test expects the call
> to fail and errno to be set to EINVAL.
>
> Using the compat syscall fixes the issue.
>
> Fixes: 7a35397f8c06 ("io_pgetevents: use __kernel_timespec")
> Signed-off-by: Richard Palethorpe
Thanks a lot for finding this, indeed there is definitely a mistake that
this function is defined and not used, but I don't yet see how it would
get to the specific failure you report.
Between the two implementations, I can see a difference in the
handling of the signal mask, but that should only affect architectures
with incompatible compat_sigset_t, i.e. big-endian or
_COMPAT_NSIG_WORDS!=_NSIG_WORDS, and the latter is
never true for currently supported architectures. On x86, there is
no difference in the sigset at all.
The negative 'nr' and 'min_nr' arguments that you list as causing
the problem /should/ be converted by the magic
SYSCALL_DEFINE6() definition. If this is currently broken, I would
expect other syscalls to be affected as well.
Have you tried reproducing this on non-x86 architectures? If I
misremembered how the compat conversion in SYSCALL_DEFINE6()
works, then all architectures that support CONFIG_COMPAT have
to be fixed.
Arnd
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