From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42664) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cReM4-0005og-8I for qemu-devel@nongnu.org; Thu, 12 Jan 2017 07:19:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cReLz-0003wg-8I for qemu-devel@nongnu.org; Thu, 12 Jan 2017 07:19:44 -0500 Date: Thu, 12 Jan 2017 12:19:34 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20170112121933.GB2513@work-vm> References: <1484216631-30723-1-git-send-email-thuth@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1484216631-30723-1-git-send-email-thuth@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2] monitor: Fix crashes when using HMP commands without CPU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Thomas Huth Cc: qemu-devel@nongnu.org, qemu-trivial@nongnu.org, Markus Armbruster , Daniel P Berrange * Thomas Huth (thuth@redhat.com) wrote: > 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. > > Signed-off-by: Thomas Huth > --- > 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; > + } OK, that includes UNASSIGNED_CPU_INDEX. > + > + qmp_memsave(addr, size, filename, true, cpu_index, &err); > hmp_handle_error(mon, &err); > } > > diff --git a/monitor.c b/monitor.c > index 0841d43..74843eb 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 : -1; > } OK, do you think that should use UNASSIGNED_CPU_INDEX explicitly rather than -1 ? > > 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; > + } > > 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; > } > -- > 1.8.3.1 Reviewed-by: Dr. David Alan Gilbert I'm sure we'll find loads more similar cases where -M none breaks stuff. (I see you've cc'd to trivial so I'll let them take it). Dave -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK