check for valid vfu_setup_region() flags (#579)

Complain about a region that isn't readable *or* writable, or any unknown flags.

Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Thanos Makatos <thanos.makatos@nutanix.com>

1 files changed, 11 insertions, 5 deletions

diff --git a/lib/libvfio-user.c b/lib/libvfio-user.c
index 1ee4026..c9c78d6 100644
--- a/lib/libvfio-user.c
+++ b/lib/libvfio-user.c
@@ -1430,6 +1430,17 @@ vfu_setup_region(vfu_ctx_t *vfu_ctx, int region_idx, size_t size,
 
     assert(vfu_ctx != NULL);
 
+    if ((flags & ~(VFU_REGION_FLAG_MASK)) ||
+        (!(flags & VFU_REGION_FLAG_RW))) {
+        vfu_log(vfu_ctx, LOG_ERR, "invalid region flags");
+        return ERROR_INT(EINVAL);
+    }
+
+    if ((flags & VFU_REGION_FLAG_ALWAYS_CB) && (cb == NULL)) {
+        vfu_log(vfu_ctx, LOG_ERR, "VFU_REGION_FLAG_ALWAYS_CB needs callback");
+        return ERROR_INT(EINVAL);
+    }
+
     if ((mmap_areas == NULL) != (nr_mmap_areas == 0) ||
         (mmap_areas != NULL && fd == -1)) {
         vfu_log(vfu_ctx, LOG_ERR, "invalid mappable region arguments");
@@ -1451,11 +1462,6 @@ vfu_setup_region(vfu_ctx_t *vfu_ctx, int region_idx, size_t size,
         return ERROR_INT(EINVAL);
     }
 
-    if ((flags & VFU_REGION_FLAG_ALWAYS_CB) && (cb == NULL)) {
-        vfu_log(vfu_ctx, LOG_ERR, "VFU_REGION_FLAG_ALWAYS_CB needs callback");
-        return ERROR_INT(EINVAL);
-    }
-
     if (region_idx == VFU_PCI_DEV_MIGR_REGION_IDX &&
         size < vfu_get_migr_register_area_size()) {
         vfu_log(vfu_ctx, LOG_ERR, "invalid migration region size %zu", size);