On Tue, Sep 21, 2021 at 3:01 PM Richard Palethorpe rpalethorpe@suse.com 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 rpalethorpe@suse.com
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