[Qemu-devel] [PATCH v3 1/2] blockdev: Error out on negative throttling option values

[Fam Zheng <famz@redhat.com>]

The implicit casting from unsigned int to double changes negative values
into large positive numbers and accepts them.  We should instead print
an error.

Check the number range so this case is caught and reported.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 blockdev.c              |  3 ++-
 include/qemu/throttle.h |  2 ++
 util/throttle.c         | 16 ++++++----------
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 2df0c6d..1afef87 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -348,7 +348,8 @@ static bool check_throttle_config(ThrottleConfig *cfg, Error **errp)
     }
 
     if (!throttle_is_valid(cfg)) {
-        error_setg(errp, "bps/iops/maxs values must be 0 or greater");
+        error_setg(errp, "bps/iops/maxs values must be within [0, %" PRId64
+                         ")", (int64_t)THROTTLE_VALUE_MAX);
         return false;
     }
 
diff --git a/include/qemu/throttle.h b/include/qemu/throttle.h
index 12faaad..d0c98ed 100644
--- a/include/qemu/throttle.h
+++ b/include/qemu/throttle.h
@@ -29,6 +29,8 @@
 #include "qemu-common.h"
 #include "qemu/timer.h"
 
+#define THROTTLE_VALUE_MAX 1000000000000000LL
+
 typedef enum {
     THROTTLE_BPS_TOTAL,
     THROTTLE_BPS_READ,
diff --git a/util/throttle.c b/util/throttle.c
index 1113671..af4bc95 100644
--- a/util/throttle.c
+++ b/util/throttle.c
@@ -282,22 +282,18 @@ bool throttle_conflicting(ThrottleConfig *cfg)
  */
 bool throttle_is_valid(ThrottleConfig *cfg)
 {
-    bool invalid = false;
     int i;
 
     for (i = 0; i < BUCKETS_COUNT; i++) {
-        if (cfg->buckets[i].avg < 0) {
-            invalid = true;
+        if (cfg->buckets[i].avg < 0 ||
+            cfg->buckets[i].max < 0 ||
+            cfg->buckets[i].avg > THROTTLE_VALUE_MAX ||
+            cfg->buckets[i].max > THROTTLE_VALUE_MAX) {
+            return false;
         }
     }
 
-    for (i = 0; i < BUCKETS_COUNT; i++) {
-        if (cfg->buckets[i].max < 0) {
-            invalid = true;
-        }
-    }
-
-    return !invalid;
+    return true;
 }
 
 /* check if bps_max/iops_max is used without bps/iops
-- 
2.4.3