blockdev: Error out on negative throttling option values

extract_common_blockdev_options() uses qemu_opt_get_number() to parse
the bps/iops numbers to uint64_t, then converts to double and stores in
ThrottleConfig.  The actual parsing is done by strtoull() in
parse_option_number().  Negative numbers are wrapped to large positive
ones, and stored.

We used to reject negative numbers since 7d81c1413c9, but this regressed
when the option parsing code was changed later. Now fix this again.

This time, define an arbitrary large upper limit (1e15),  and check the
values so both negative and impractically big numbers are caught and
reported.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

3 files changed, 10 insertions, 11 deletions

diff --git a/blockdev.c b/blockdev.c
index 1392fff..07cfe25 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/max values must be within [0, %lld]",
+                   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