Commit 399ba75fbe for qemu.org

commit 399ba75fbe308f179da48d183bd48d662ee16199
Author: Song Gao <17746591750@163.com>
Date:   Wed Jul 1 14:54:54 2026 +0800

    hw/intc/loongarch_dintc: Fix OOB access in DINT MMIO write handler

    Validate guest-controlled cpu_num before using it to index the cpu[] array
    or pass to async_run_on_cpu(). Without this check, a malicious guest can
    trigger a NULL pointer dereference in async_run_on_cpu() and an
    out-of-bounds array access in qemu_set_irq(), causing host crash.

    Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3616
    Fixes: 0d148eaf5a3e ("hw/loongarch: Implement dintc set irq")
    Reported-by: Thomas Huth <thuth@redhat.com>
    Signed-off-by: Song Gao <gaosong@loongson.cn>
    Reviewed-by: Thomas Huth <thuth@redhat.com>
    Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>
    Message-ID: <20260701065454.1976188-1-gaosong@loongson.cn>
    Signed-off-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>

diff --git a/hw/intc/loongarch_dintc.c b/hw/intc/loongarch_dintc.c
index c877a8003b..e40292887c 100644
--- a/hw/intc/loongarch_dintc.c
+++ b/hw/intc/loongarch_dintc.c
@@ -19,6 +19,7 @@
 #include "target/loongarch/cpu.h"
 #include "qemu/error-report.h"
 #include "system/hw_accel.h"
+#include "qemu/log.h"

 /* msg addr field */
 FIELD(MSG_ADDR, IRQ_NUM, 4, 8)
@@ -52,7 +53,19 @@ static void loongarch_dintc_mem_write(void *opaque, hwaddr addr,
     CPUState *cs;

     cpu_num = FIELD_EX64(msg_addr, MSG_ADDR, CPU_NUM);
+
+    /* Validate cpu_num against the configured number of CPUs */
+    if (cpu_num >= s->num_cpu) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "loongarch-dintc: invalid cpu number%d\n", cpu_num);
+        return;
+    }
     cs = cpu_by_arch_id(cpu_num);
+    if (!cs) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "loongarch-dintc: no CPU for arch_id %d\n", cpu_num);
+        return;
+    }
     irq_num = FIELD_EX64(msg_addr, MSG_ADDR, IRQ_NUM);

     async_run_on_cpu(cs, do_set_vcpu_dintc_irq,