io_uring: fix big-endian compat signal mask handling

commit 9e75ad5d8f399a21c86271571aa630dd080223e2 upstream.

On big-endian architectures, the signal masks are differnet
between 32-bit and 64-bit tasks, so we have to use a different
function for reading them from user space.

io_cqring_wait() initially got this wrong, and always interprets
this as a native structure. This is ok on x86 and most arm64,
but not on s390, ppc64be, mips64be, sparc64 and parisc.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NJeffle Xu <jefflexu@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

fs/io_uring.c

@@ -1968,7 +1968,15 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 		return 0;
 
 	if (sig) {
-		ret = set_user_sigmask(sig, &ksigmask, &sigsaved, sigsz);
+#ifdef CONFIG_COMPAT
+		if (in_compat_syscall())
+			ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
+						      &ksigmask, &sigsaved, sigsz);
+		else
+#endif
+			ret = set_user_sigmask(sig, &ksigmask,
+					       &sigsaved, sigsz);
+
 		if (ret)
 			return ret;
 	}