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[PATCH v5 02/14] perf tools: Prevent calling machine__delete() on non-allocated machine

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  [PATCH v5 02/14] perf tools: Prevent calling machine__delete() on non-allocated machine Wang Nan <wangnan0@huawei.com> - 2015-12-14 11:50 +0100
    Re: [PATCH v5 02/14] perf tools: Prevent calling machine__delete()  on non-allocated machine Jiri Olsa <jolsa@redhat.com> - 2015-12-15 13:40 +0100
      Re: [PATCH v5 02/14] perf tools: Prevent calling machine__delete()  on non-allocated machine "Wangnan (F)" <wangnan0@huawei.com> - 2015-12-16 02:40 +0100
        Re: [PATCH v5 02/14] perf tools: Prevent calling machine__delete()  on non-allocated machine Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-12-16 20:50 +0100

#1291094 — [PATCH v5 02/14] perf tools: Prevent calling machine__delete() on non-allocated machine

To prevent futher commits calling machine__delete() on non-allocated
'struct machine' (which would cause memory corruption), this patch
enforces machine__init(), record whether a machine structure is
dynamically allocated or not, and warn if machine__delete() is called
on incorrect object.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/tests/vmlinux-kallsyms.c |  4 ++--
 tools/perf/util/machine.c           | 14 +++++++++-----
 tools/perf/util/machine.h           |  3 ++-
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/tools/perf/tests/vmlinux-kallsyms.c b/tools/perf/tests/vmlinux-kallsyms.c
index f0bfc9e..441e93d 100644
--- a/tools/perf/tests/vmlinux-kallsyms.c
+++ b/tools/perf/tests/vmlinux-kallsyms.c
@@ -35,8 +35,8 @@ int test__vmlinux_matches_kallsyms(int subtest __maybe_unused)
 	 * Init the machines that will hold kernel, modules obtained from
 	 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
 	 */
-	machine__init(&kallsyms, "", HOST_KERNEL_ID);
-	machine__init(&vmlinux, "", HOST_KERNEL_ID);
+	machine__init(&kallsyms, "", HOST_KERNEL_ID, false);
+	machine__init(&vmlinux, "", HOST_KERNEL_ID, false);
 
 	/*
 	 * Step 2:
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index ad79297..955341a 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -23,7 +23,7 @@ static void dsos__init(struct dsos *dsos)
 	pthread_rwlock_init(&dsos->lock, NULL);
 }
 
-int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
+int machine__init(struct machine *machine, const char *root_dir, pid_t pid, bool allocated)
 {
 	memset(machine, 0, sizeof(*machine));
 	map_groups__init(&machine->kmaps, machine);
@@ -65,6 +65,7 @@ int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
 	}
 
 	machine->current_tid = NULL;
+	machine->allocated = allocated;
 
 	return 0;
 }
@@ -74,7 +75,7 @@ struct machine *machine__new_host(void)
 	struct machine *machine = malloc(sizeof(*machine));
 
 	if (machine != NULL) {
-		machine__init(machine, "", HOST_KERNEL_ID);
+		machine__init(machine, "", HOST_KERNEL_ID, true);
 
 		if (machine__create_kernel_maps(machine) < 0)
 			goto out_delete;
@@ -137,12 +138,15 @@ void machine__exit(struct machine *machine)
 void machine__delete(struct machine *machine)
 {
 	machine__exit(machine);
-	free(machine);
+	if (machine->allocated)
+		free(machine);
+	else
+		pr_warning("WARNING: delete a non-allocated machine. Skip.\n");
 }
 
 void machines__init(struct machines *machines)
 {
-	machine__init(&machines->host, "", HOST_KERNEL_ID);
+	machine__init(&machines->host, "", HOST_KERNEL_ID, false);
 	machines->guests = RB_ROOT;
 	machines->symbol_filter = NULL;
 }
@@ -163,7 +167,7 @@ struct machine *machines__add(struct machines *machines, pid_t pid,
 	if (machine == NULL)
 		return NULL;
 
-	if (machine__init(machine, root_dir, pid) != 0) {
+	if (machine__init(machine, root_dir, pid, true) != 0) {
 		free(machine);
 		return NULL;
 	}
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index 2c2b443..24dfd46 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -28,6 +28,7 @@ struct machine {
 	pid_t		  pid;
 	u16		  id_hdr_size;
 	bool		  comm_exec;
+	bool		  allocated;
 	char		  *root_dir;
 	struct rb_root	  threads;
 	pthread_rwlock_t  threads_lock;
@@ -131,7 +132,7 @@ void machines__set_symbol_filter(struct machines *machines,
 void machines__set_comm_exec(struct machines *machines, bool comm_exec);
 
 struct machine *machine__new_host(void);
-int machine__init(struct machine *machine, const char *root_dir, pid_t pid);
+int machine__init(struct machine *machine, const char *root_dir, pid_t pid, bool allocated);
 void machine__exit(struct machine *machine);
 void machine__delete_threads(struct machine *machine);
 void machine__delete(struct machine *machine);
-- 
1.8.3.4

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#1292115 — Re: [PATCH v5 02/14] perf tools: Prevent calling machine__delete() on non-allocated machine

On Mon, Dec 14, 2015 at 10:39:11AM +0000, Wang Nan wrote:

SNIP

> @@ -137,12 +138,15 @@ void machine__exit(struct machine *machine)
>  void machine__delete(struct machine *machine)
>  {
>  	machine__exit(machine);
> -	free(machine);
> +	if (machine->allocated)
> +		free(machine);
> +	else
> +		pr_warning("WARNING: delete a non-allocated machine. Skip.\n");

we used WARN_ONCE several times already in similar cases

jirka
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#1292693 — Re: [PATCH v5 02/14] perf tools: Prevent calling machine__delete() on non-allocated machine

On 2015/12/15 20:36, Jiri Olsa wrote:
> On Mon, Dec 14, 2015 at 10:39:11AM +0000, Wang Nan wrote:
>
> SNIP
>
>> @@ -137,12 +138,15 @@ void machine__exit(struct machine *machine)
>>   void machine__delete(struct machine *machine)
>>   {
>>   	machine__exit(machine);
>> -	free(machine);
>> +	if (machine->allocated)
>> +		free(machine);
>> +	else
>> +		pr_warning("WARNING: delete a non-allocated machine. Skip.\n");
> we used WARN_ONCE several times already in similar cases
>
> jirka

Will switch to:

@@ -136,13 +138,13 @@ void machine__exit(struct machine *machine)

  void machine__delete(struct machine *machine)
  {
-       machine__exit(machine);
-       free(machine);
+       WARN_ONCE((machine->allocated ? free(machine), 0 : -1),
+                 "WARNING: deleting a non-allocated machine. Skip.\n");
  }

Thank you.

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#1293330 — Re: [PATCH v5 02/14] perf tools: Prevent calling machine__delete() on non-allocated machine

Em Wed, Dec 16, 2015 at 09:37:18AM +0800, Wangnan (F) escreveu:
> 
> 
> On 2015/12/15 20:36, Jiri Olsa wrote:
> >On Mon, Dec 14, 2015 at 10:39:11AM +0000, Wang Nan wrote:
> >
> >SNIP
> >
> >>@@ -137,12 +138,15 @@ void machine__exit(struct machine *machine)
> >>  void machine__delete(struct machine *machine)
> >>  {
> >>  	machine__exit(machine);
> >>-	free(machine);
> >>+	if (machine->allocated)
> >>+		free(machine);
> >>+	else
> >>+		pr_warning("WARNING: delete a non-allocated machine. Skip.\n");
> >we used WARN_ONCE several times already in similar cases
> >
> >jirka
> 
> Will switch to:
> 
> @@ -136,13 +138,13 @@ void machine__exit(struct machine *machine)
> 
>  void machine__delete(struct machine *machine)
>  {
> -       machine__exit(machine);

Better keep the above.

And I wonder if we would go on sprinkling these kinds of checks for all
classes we have :-\

I think this is a job for some static analisys tool, that or we figure
out a way to find out if an address is for a stack or heap and use that
instead, and in a bpf based tool, perhaps, one that would hook into all
*__delete() tools and check if the object it is using should or not be
in fact free()ed.

I could think about hooking __new*() calls, hashing the return value,
then at __delete() time check it, for instance.

- Arnaldo

> -       free(machine);
> +       WARN_ONCE((machine->allocated ? free(machine), 0 : -1),
> +                 "WARNING: deleting a non-allocated machine. Skip.\n");
>  }
> 
> Thank you.
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