Re: [PATCH 2/5] hw/intc/loongarch_pch_pic: Fix coverity errors in update irq

[Richard Henderson]

On 7/13/22 15:20, Xiaojuan Yang wrote:

Fix coverity errors:
1. In find_first_bit function, the 'size' argument need
'unsigned long' type, so we change the 'size' to unsigned
long type when use the function.
2. In expression 1ULL << irq, left shifting by more than
63 bits has undefined behavior. And out-of-bounds access
error occured when 'irq' >= 64. So we add a condition to
avoid this.
3. Use 'MAKE_64BIT_MASK(irq, 1)' to replace '1ULL << shift'.

Fix coverity CID: 1489761 1489764 1489765

Signed-off-by: Xiaojuan Yang <yangxiaoj...@loongson.cn>
---
  hw/intc/loongarch_pch_pic.c | 19 ++++++++++++-------
  1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/hw/intc/loongarch_pch_pic.c b/hw/intc/loongarch_pch_pic.c
index 3c9814a3b4..040b89861c 100644
--- a/hw/intc/loongarch_pch_pic.c
+++ b/hw/intc/loongarch_pch_pic.c
@@ -15,22 +15,27 @@

static void pch_pic_update_irq(LoongArchPCHPIC *s, uint64_t mask, int level)

  {
-    unsigned long val;
+    unsigned long val, max_irq;

You did not follow any of my direction from v1.

(1) val must be uint64_t.

(and, generally, any use of 'unsigned long' is probably a bug)

+            irq = find_first_bit(&val, max_irq);

Use ctz64().

+            if (irq < max_irq) {

This, really, should be a test of val != 0 before the ctz.

+                s->intisr |= MAKE_64BIT_MASK(irq, 1);
+                qemu_set_irq(s->parent_irq[s->htmsi_vector[irq]], 1);
+            }
          }
      } else {
          val = mask & s->intisr;
          if (val) {
-            irq = find_first_bit(&val, 64);
-            s->intisr &= ~(0x1ULL << irq);
-            qemu_set_irq(s->parent_irq[s->htmsi_vector[irq]], 0);
+            irq = find_first_bit(&val, max_irq);
+            if (irq < max_irq) {
+                s->intisr &= ~(MAKE_64BIT_MASK(irq, 1));
+                qemu_set_irq(s->parent_irq[s->htmsi_vector[irq]], 0);

etc.


r~

+            }
          }
      }
  }