tools/virtio: check mmap return value in vringh_test

[ Upstream commit ec6177d ]

In parallel_test(), the return values of mmap() for both host_map and
guest_map are not checked against MAP_FAILED. If mmap() fails, the
subsequent code will dereference the invalid pointer, leading to a
segmentation fault.

Add MAP_FAILED checks after both mmap() calls, using err() to report
the error and exit, consistent with the existing error handling style
in this file (e.g., the open() call on line 149).

Fixes: 1515c5c ("tools/virtio: add vring_test.")
Signed-off-by: longlong yan <yanlonglong@kylinos.cn>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260605021446.1611-1-yanlonglong@kylinos.cn>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: longlong yan

tools/virtio/vringh_test.c

@@ -159,7 +159,12 @@ static int parallel_test(u64 features,
 
 	/* Parent and child use separate addresses, to check our mapping logic! */
 	host_map = mmap(NULL, mapsize, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+	if (host_map == MAP_FAILED)
+		err(1, "mmap host_map");
+
 	guest_map = mmap(NULL, mapsize, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+	if (guest_map == MAP_FAILED)
+		err(1, "mmap guest_map");
 
 	pipe(to_guest);
 	pipe(to_host);