Richard Palethorpe rpalethorpe@suse.de writes:
Richard Palethorpe rpalethorpe@suse.de writes:
Hello Arnd,
Arnd Bergmann arnd@arndb.de writes:
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.
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.
ArndNo, 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);@@ -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
and below is the macro expansion for the automatically generated 32bit to 64bit io_pgetevents. I believe it is casting u32 to s64, which appears to mean there is no sign extension. I don't know if this is the expected behaviour?
For the manually written compat version we cast back to s32 which is what fixes the issue.
long __ia32_sys_io_pgetevents(const struct pt_regs *regs) { return __se_sys_io_pgetevents((unsigned int)regs->bx, (unsigned int)regs->cx, (unsigned int)regs->dx, (unsigned int)regs->si, (unsigned int)regs->di, (unsigned int)regs->bp); } static long __se_sys_io_pgetevents( __typeof(__builtin_choose_expr( (__builtin_types_compatible_p(typeof((aio_context_t)0), typeof(0LL)) || __builtin_types_compatible_p(typeof((aio_context_t)0), typeof(0ULL))), 0LL, 0L)) ctx_id, __typeof(__builtin_choose_expr( (__builtin_types_compatible_p(typeof((long)0), typeof(0LL)) || __builtin_types_compatible_p(typeof((long)0), typeof(0ULL))), 0LL, 0L)) min_nr, __typeof(__builtin_choose_expr( (__builtin_types_compatible_p(typeof((long)0), typeof(0LL)) || __builtin_types_compatible_p(typeof((long)0), typeof(0ULL))), 0LL, 0L)) nr, __typeof(__builtin_choose_expr( (__builtin_types_compatible_p(typeof((struct io_event *)0), typeof(0LL)) || __builtin_types_compatible_p(typeof((struct io_event *)0), typeof(0ULL))), 0LL, 0L)) events, __typeof(__builtin_choose_expr( (__builtin_types_compatible_p(typeof((struct __kernel_timespec *)0), typeof(0LL)) || __builtin_types_compatible_p(typeof((struct __kernel_timespec *)0), typeof(0ULL))), 0LL, 0L)) timeout, __typeof(__builtin_choose_expr( (__builtin_types_compatible_p(typeof((const struct __aio_sigset *)0), typeof(0LL)) || __builtin_types_compatible_p(typeof((const struct __aio_sigset *)0), typeof(0ULL))), 0LL, 0L)) usig) { long ret = __do_sys_io_pgetevents( (aio_context_t)ctx_id, (long)min_nr, (long)nr, (struct io_event *)events, (struct __kernel_timespec *)timeout, (const struct __aio_sigset *)usig);
... }