[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-trivial] [Qemu-devel] [PATCH v3] monitor: Fix crashes when usi
From: |
Thomas Huth |
Subject: |
Re: [Qemu-trivial] [Qemu-devel] [PATCH v3] monitor: Fix crashes when using HMP commands without CPU |
Date: |
Thu, 12 Jan 2017 18:34:45 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 |
On 12.01.2017 17:22, Markus Armbruster wrote:
> Thomas Huth <address@hidden> writes:
>
>> When running certain HMP commands ("info registers", "info cpustats",
>> "nmi", "memsave" 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, but these HMP commands did
>> not check for a valid CPU pointer yet. Add such checks now, so we get
>> an error message about the missing CPU instead.
>>
>> Reviewed-by: Dr. David Alan Gilbert <address@hidden>
>> Signed-off-by: Thomas Huth <address@hidden>
>> ---
>> v3:
>> - Use UNASSIGNED_CPU_INDEX instead of hard-coded -1
>> v2:
>> - Added more checks to cover "nmi" and "memsave", too
>>
>> hmp.c | 8 +++++++-
>> monitor.c | 37 +++++++++++++++++++++++++++++++------
>> 2 files changed, 38 insertions(+), 7 deletions(-)
>>
>> diff --git a/hmp.c b/hmp.c
>> index b869617..b1c503a 100644
>> --- a/hmp.c
>> +++ b/hmp.c
>> @@ -1013,8 +1013,14 @@ void hmp_memsave(Monitor *mon, const QDict *qdict)
>> const char *filename = qdict_get_str(qdict, "filename");
>> uint64_t addr = qdict_get_int(qdict, "val");
>> Error *err = NULL;
>> + int cpu_index = monitor_get_cpu_index();
>>
>> - qmp_memsave(addr, size, filename, true, monitor_get_cpu_index(), &err);
>> + if (cpu_index < 0) {
>> + monitor_printf(mon, "No CPU available\n");
>> + return;
>> + }
>> +
>> + qmp_memsave(addr, size, filename, true, cpu_index, &err);
>> hmp_handle_error(mon, &err);
>> }
>>
>> diff --git a/monitor.c b/monitor.c
>> index 0841d43..17121ff 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);
>> @@ -1033,17 +1036,27 @@ CPUState *mon_get_cpu(void)
>>
>> CPUArchState *mon_get_cpu_env(void)
>> {
>> - return mon_get_cpu()->env_ptr;
>> + CPUState *cs = mon_get_cpu();
>> +
>> + return cs ? cs->env_ptr : NULL;
>> }
>>
>> int monitor_get_cpu_index(void)
>> {
>> - return mon_get_cpu()->cpu_index;
>> + CPUState *cs = mon_get_cpu();
>> +
>> + return cs ? cs->cpu_index : UNASSIGNED_CPU_INDEX;
>> }
>>
>> 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 +1089,13 @@ 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 +1254,12 @@ 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;
>> + }
>
> This is basically "if (we're going to dereference cs)". Not so nice, in
> particular since the dereferences are hidden inside mon_get_cpu_env()
> calls. I guess it'll do.
>
>>
>> if (format == 'i') {
>> int flags = 0;
>> @@ -1264,7 +1289,7 @@ 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 +1328,7 @@ 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;
>> }
>
> What about get_monitor_def()?
>
> $ qemu-system-x86_64 --nodefaults -S -display none -M none -monitor stdio
> QEMU 2.8.50 monitor - type 'help' for more information
> (qemu) p $pc
> Segmentation fault (core dumped)
Oh, I saw that get_monitor_def() uses mon_get_cpu_env(), but I only
checked with qemu-system-m68k where "p $pc" simply prints "unknown
register" when you run it with the "none" machine ... that's why I
assumed that no fixes would be needed here.
> Likewise, info tlb, info mem, ...
These seem to be target specific, too, so I think they could go into a
separate patch instead. If it's OK for you, I'd like to keep my current
patch as it is, and add these items to
http://qemu-project.org/BiteSizedTasks instead - since these are all
non-urgent problems that should be easy to fix for newcomers, too.
Thomas