[PATCH] hw/intc: sifive_plic: Avoid overflowing the addr_config buffer

[Alistair Francis <alistair.francis@opensource.wdc.com>]

From: Alistair Francis <alistair.francis@wdc.com>

Since commit ad40be27 "target/riscv: Support start kernel directly by
KVM" we have been overflowing the addr_config on "M,MS..."
configurations, as reported https://gitlab.com/qemu-project/qemu/-/issues/1050.

This commit changes the loop in sifive_plic_create() from iterating over
the number of harts to just iterating over the addr_config. The
addr_config is based on the hart_config, and will contain interrup details
for all harts. This way we can't iterate past the end of addr_config.

Fixes: ad40be27084536 ("target/riscv: Support start kernel directly by KVM")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1050
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 hw/intc/sifive_plic.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/hw/intc/sifive_plic.c b/hw/intc/sifive_plic.c
index eebbcf33d4..56d60e9ac9 100644
--- a/hw/intc/sifive_plic.c
+++ b/hw/intc/sifive_plic.c
@@ -431,7 +431,7 @@ DeviceState *sifive_plic_create(hwaddr addr, char *hart_config,
     uint32_t context_stride, uint32_t aperture_size)
 {
     DeviceState *dev = qdev_new(TYPE_SIFIVE_PLIC);
-    int i, j = 0;
+    int i;
     SiFivePLICState *plic;
 
     assert(enable_stride == (enable_stride & -enable_stride));
@@ -451,18 +451,17 @@ DeviceState *sifive_plic_create(hwaddr addr, char *hart_config,
     sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, addr);
 
     plic = SIFIVE_PLIC(dev);
-    for (i = 0; i < num_harts; i++) {
-        CPUState *cpu = qemu_get_cpu(hartid_base + i);
 
-        if (plic->addr_config[j].mode == PLICMode_M) {
-            j++;
-            qdev_connect_gpio_out(dev, num_harts + i,
+    for (i = 0; i < plic->num_addrs; i++) {
+        int cpu_num = plic->addr_config[i].hartid;
+        CPUState *cpu = qemu_get_cpu(hartid_base + cpu_num);
+
+        if (plic->addr_config[i].mode == PLICMode_M) {
+            qdev_connect_gpio_out(dev, num_harts + cpu_num,
                                   qdev_get_gpio_in(DEVICE(cpu), IRQ_M_EXT));
         }
-
-        if (plic->addr_config[j].mode == PLICMode_S) {
-            j++;
-            qdev_connect_gpio_out(dev, i,
+        if (plic->addr_config[i].mode == PLICMode_S) {
+            qdev_connect_gpio_out(dev, cpu_num,
                                   qdev_get_gpio_in(DEVICE(cpu), IRQ_S_EXT));
         }
     }
-- 
2.35.3