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From:   Arnd Bergmann <arnd@arndb.de>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Jens Axboe <axboe@kernel.dk>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Hannes Reinecke <hare@suse.com>,
        Matthew Wilcox <willy@infradead.org>,
        David Hildenbrand <david@redhat.com>,
        Nikolay Borisov <nborisov@suse.com>,
        linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] io_uring: fix big-endian compat signal mask handling
Date:   Mon, 25 Mar 2019 15:34:53 +0100
Message-Id: <20190325143521.34928-1-arnd@arndb.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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: Arnd Bergmann <arnd@arndb.de>
---
 fs/io_uring.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6aaa30580a2b..8f48d29abf76 100644
--- a/fs/io_uring.c
+++ b/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;
 	}
-- 
2.20.0