Thomas Huth <th...@redhat.com> writes:
> When running certain HMP commands ("info registers", "info cpustats"
> or dumping virtual memory) with the "none" machine, QEMU crashes
> with a segmentation fault. This happens because the "none" machine does
> not have any CPUs by default,
"Sachen gibt's!"
> but these HMP commands did not check for
> a valid CPU pointer yet. Add such a check now and print a message
> about the missing CPU instead.
Have you checked uses of first_cpu elsewhere? Out of scope for this
patch, of course.
> Signed-off-by: Thomas Huth <th...@redhat.com>
> ---
> monitor.c | 29 +++++++++++++++++++++++++----
> 1 file changed, 25 insertions(+), 4 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index 0841d43..0103979 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -1025,6 +1025,9 @@ int monitor_set_cpu(int cpu_index)
> CPUState *mon_get_cpu(void)
> {
> if (!cur_mon->mon_cpu) {
> + if (!first_cpu) {
> + return NULL;
> + }
> monitor_set_cpu(first_cpu->cpu_index);
> }
> cpu_synchronize_state(cur_mon->mon_cpu);
Why are the following dereferences safe?
CPUArchState *mon_get_cpu_env(void)
{
return mon_get_cpu()->env_ptr;
}
int monitor_get_cpu_index(void)
{
return mon_get_cpu()->cpu_index;
}
> @@ -1043,7 +1046,13 @@ int monitor_get_cpu_index(void)
>
> static void hmp_info_registers(Monitor *mon, const QDict *qdict)
> {
> - cpu_dump_state(mon_get_cpu(), (FILE *)mon, monitor_fprintf,
> CPU_DUMP_FPU);
> + CPUState *cs = mon_get_cpu();
> +
> + if (!cs) {
> + monitor_printf(mon, "No CPU available\n");
> + return;
> + }
> + cpu_dump_state(cs, (FILE *)mon, monitor_fprintf, CPU_DUMP_FPU);
> }
>
> static void hmp_info_jit(Monitor *mon, const QDict *qdict)
> @@ -1076,7 +1085,13 @@ static void hmp_info_history(Monitor *mon, const QDict
> *qdict)
>
> static void hmp_info_cpustats(Monitor *mon, const QDict *qdict)
> {
> - cpu_dump_statistics(mon_get_cpu(), (FILE *)mon, &monitor_fprintf, 0);
> + CPUState *cs = mon_get_cpu();
> +
> + if (!cs) {
> + monitor_printf(mon, "No CPU available\n");
> + return;
> + }
> + cpu_dump_statistics(cs, (FILE *)mon, &monitor_fprintf, 0);
> }
>
> static void hmp_info_trace_events(Monitor *mon, const QDict *qdict)
> @@ -1235,6 +1250,12 @@ static void memory_dump(Monitor *mon, int count, int
> format, int wsize,
> int l, line_size, i, max_digits, len;
> uint8_t buf[16];
> uint64_t v;
> + CPUState *cs = mon_get_cpu();
> +
> + if (!cs && (format == 'i' || !is_physical)) {
> + monitor_printf(mon, "Can not dump without CPU\n");
> + return;
> + }
>
> if (format == 'i') {
> int flags = 0;
> @@ -1264,7 +1285,7 @@ static void memory_dump(Monitor *mon, int count, int
> format, int wsize,
> flags = msr_le << 16;
> flags |= env->bfd_mach;
> #endif
> - monitor_disas(mon, mon_get_cpu(), addr, count, is_physical, flags);
> + monitor_disas(mon, cs, addr, count, is_physical, flags);
> return;
> }
>
> @@ -1303,7 +1324,7 @@ static void memory_dump(Monitor *mon, int count, int
> format, int wsize,
> if (is_physical) {
> cpu_physical_memory_read(addr, buf, l);
> } else {
> - if (cpu_memory_rw_debug(mon_get_cpu(), addr, buf, l, 0) < 0) {
> + if (cpu_memory_rw_debug(cs, addr, buf, l, 0) < 0) {
> monitor_printf(mon, " Cannot access memory\n");
> break;
> }
