raw_bsd: move check to prevent overflow

When only offset is specified but no size and the offset is greater than
the real size of the containing device an overflow occurs when parsing
the options. This overflow is harmless because we do check for this
exact situation little bit later, but it leads to an error message with
weird values. It is better to do the check is sooner and prevent the
overflow.

Signed-off-by: Tomáš Golembiovský <tgolembi@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block/raw_bsd.c b/block/raw_bsd.c
index 7c9bebb..cf7a560 100644 (file)
--- a/block/raw_bsd.c
+++ b/block/raw_bsd.c
@@ -91,6 +91,14 @@ static int raw_read_options(QDict *options, BlockDriverState *bs,
     }
 
     s->offset = qemu_opt_get_size(opts, "offset", 0);
+    if (s->offset > real_size) {
+        error_setg(errp, "Offset (%" PRIu64 ") cannot be greater than "
+            "size of the containing file (%" PRId64 ")",
+            s->offset, real_size);
+        ret = -EINVAL;
+        goto end;
+    }
+
     if (qemu_opt_find(opts, "size") != NULL) {
         s->size = qemu_opt_get_size(opts, "size", 0);
         s->has_size = true;
@@ -100,7 +108,7 @@ static int raw_read_options(QDict *options, BlockDriverState *bs,
     }
 
     /* Check size and offset */
-    if (real_size < s->offset || (real_size - s->offset) < s->size) {
+    if ((real_size - s->offset) < s->size) {
         error_setg(errp, "The sum of offset (%" PRIu64 ") and size "
             "(%" PRIu64 ") has to be smaller or equal to the "
             " actual size of the containing file (%" PRId64 ")",