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 <[email protected]> Signed-off-by: Song Gao <[email protected]> --- hw/intc/loongarch_dintc.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) 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, -- 2.47.3
