ivshmem: check shm isn't already initialized

The server should not change the shm, and this isn't handled by qemu and
we should should verify this in qemu.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Claudio Fontana <claudio.fontana@huawei.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index d3d0204..9023f95 100644
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -533,6 +533,12 @@ static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
     if (incoming_posn == -1) {
         void * map_ptr;
 
+        if (s->shm_fd >= 0) {
+            error_report("shm already initialized");
+            close(incoming_fd);
+            return;
+        }
+
         if (check_shm_size(s, incoming_fd, &err) == -1) {
             error_report_err(err);
             close(incoming_fd);