[PATCH BlueZ] client: Fix segmentation fault while fetching advertising data

[PATCH BlueZ] client: Fix segmentation fault while fetching advertising data

[Anupam Roy]

While testing advertisement, I encountered Seg fault in client, when bluetoothd
tries to fetch the Adv data set by client. It can happen either while fetching
Manufacturer specific data or Service data. Backtrace is provided below for reference
After fix is applied, advertisement works fine for me. I am sending the following patch
your review. Thank you.

Passing val instead of &val in dbus_message_iter_append_fixed_array
DBUS API causes segmentation fault while fecthing Manufacturer
data or service data set by client.

BT Before Fix:
[bluetooth]# set-advertise-name Test
[bluetooth]# set-advertise-uuids 0x1824
[bluetooth]# set-advertise-manufacturer 0x75 0x02 0x03 0x04
[bluetooth]# advertise on

Program received signal SIGSEGV, Segmentation fault.
in append_array_variant(iter=iter@entry=0x7fffffffd780,
val=val@entry=0x62485a <ad+90>, n_elements=n_elements@entry=3, type=121) at client/advertising.c:178
in dict_append_basic_array(type=121, n_elements=3,
val=0x62485a <ad+90>, key=0x624858 <ad+88>, key_type=113, dict=0x7fffffffd730) at client/advertising.c:205
get_manufacturer_data(property=<optimized out>, iter=0x7fffffffd840,
user_data=<optimized out>) at client/advertising.c:253

After Fix:
[bluetooth]# set-advertise-name Test
[bluetooth]# set-advertise-uuids 0x1824
[bluetooth]# set-advertise-manufacturer 0x75 0x02 0x03 0x04
[bluetooth]# advertise on
[CHG] Controller 00:19:0E:11:55:44 SupportedInstances: 0x04
[CHG] Controller 00:19:0E:11:55:44 ActiveInstances: 0x01
Advertising object registered
[bluetooth]#
---
 client/advertising.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/client/advertising.c b/client/advertising.c
index 76cee3d..7d98ae3 100644
--- a/client/advertising.c
+++ b/client/advertising.c
@@ -175,7 +175,7 @@ static void append_array_variant(DBusMessageIter *iter, int type, void *val,
 						type_sig, &array);
 
 	if (dbus_type_is_fixed(type) == TRUE) {
-		dbus_message_iter_append_fixed_array(&array, type, val,
+		dbus_message_iter_append_fixed_array(&array, type, &val,
 							n_elements);
 	} else if (type == DBUS_TYPE_STRING || type == DBUS_TYPE_OBJECT_PATH) {
 		const char ***str_array = val;
-- 
1.9.1

Re: [PATCH BlueZ] client: Fix segmentation fault while fetching advertising data

[Luiz Augusto von Dentz]

Hi Anupam,

On Wed, Oct 25, 2017 at 9:39 AM, Anupam Roy <anupam.r@samsung.com> wrote:
> While testing advertisement, I encountered Seg fault in client, when bluetoothd
> tries to fetch the Adv data set by client. It can happen either while fetching
> Manufacturer specific data or Service data. Backtrace is provided below for reference
> After fix is applied, advertisement works fine for me. I am sending the following patch
> your review. Thank you.
>
> Passing val instead of &val in dbus_message_iter_append_fixed_array
> DBUS API causes segmentation fault while fecthing Manufacturer
> data or service data set by client.
>
> BT Before Fix:
> [bluetooth]# set-advertise-name Test
> [bluetooth]# set-advertise-uuids 0x1824
> [bluetooth]# set-advertise-manufacturer 0x75 0x02 0x03 0x04
> [bluetooth]# advertise on
>
> Program received signal SIGSEGV, Segmentation fault.
> in append_array_variant(iter=iter@entry=0x7fffffffd780,
> val=val@entry=0x62485a <ad+90>, n_elements=n_elements@entry=3, type=121) at client/advertising.c:178
> in dict_append_basic_array(type=121, n_elements=3,
> val=0x62485a <ad+90>, key=0x624858 <ad+88>, key_type=113, dict=0x7fffffffd730) at client/advertising.c:205
> get_manufacturer_data(property=<optimized out>, iter=0x7fffffffd840,
> user_data=<optimized out>) at client/advertising.c:253
>
> After Fix:
> [bluetooth]# set-advertise-name Test
> [bluetooth]# set-advertise-uuids 0x1824
> [bluetooth]# set-advertise-manufacturer 0x75 0x02 0x03 0x04
> [bluetooth]# advertise on
> [CHG] Controller 00:19:0E:11:55:44 SupportedInstances: 0x04
> [CHG] Controller 00:19:0E:11:55:44 ActiveInstances: 0x01
> Advertising object registered
> [bluetooth]#
> ---
>  client/advertising.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/client/advertising.c b/client/advertising.c
> index 76cee3d..7d98ae3 100644
> --- a/client/advertising.c
> +++ b/client/advertising.c
> @@ -175,7 +175,7 @@ static void append_array_variant(DBusMessageIter *iter, int type, void *val,
>                                                 type_sig, &array);
>
>         if (dbus_type_is_fixed(type) == TRUE) {
> -               dbus_message_iter_append_fixed_array(&array, type, val,
> +               dbus_message_iter_append_fixed_array(&array, type, &val,
>                                                         n_elements);
>         } else if (type == DBUS_TYPE_STRING || type == DBUS_TYPE_OBJECT_PATH) {
>                 const char ***str_array = val;
> --
> 1.9.1

Thanks for the patch but the proper fix is to call dict_append_array
with correct pointer otherwise this API will not be consistent with
libdbus, so we may want to have pointer to &ad->data and then pass its
address there.

>
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-- 
Luiz Augusto von Dentz

Re: [PATCH BlueZ] client: Fix segmentation fault while fetching advertising data

[Luiz Augusto von Dentz]

Hi Anupam,

On Thu, Oct 26, 2017 at 3:29 PM, Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
> Hi Anupam,
>
> On Wed, Oct 25, 2017 at 9:39 AM, Anupam Roy <anupam.r@samsung.com> wrote:
>> While testing advertisement, I encountered Seg fault in client, when bluetoothd
>> tries to fetch the Adv data set by client. It can happen either while fetching
>> Manufacturer specific data or Service data. Backtrace is provided below for reference
>> After fix is applied, advertisement works fine for me. I am sending the following patch
>> your review. Thank you.
>>
>> Passing val instead of &val in dbus_message_iter_append_fixed_array
>> DBUS API causes segmentation fault while fecthing Manufacturer
>> data or service data set by client.
>>
>> BT Before Fix:
>> [bluetooth]# set-advertise-name Test
>> [bluetooth]# set-advertise-uuids 0x1824
>> [bluetooth]# set-advertise-manufacturer 0x75 0x02 0x03 0x04
>> [bluetooth]# advertise on
>>
>> Program received signal SIGSEGV, Segmentation fault.
>> in append_array_variant(iter=iter@entry=0x7fffffffd780,
>> val=val@entry=0x62485a <ad+90>, n_elements=n_elements@entry=3, type=121) at client/advertising.c:178
>> in dict_append_basic_array(type=121, n_elements=3,
>> val=0x62485a <ad+90>, key=0x624858 <ad+88>, key_type=113, dict=0x7fffffffd730) at client/advertising.c:205
>> get_manufacturer_data(property=<optimized out>, iter=0x7fffffffd840,
>> user_data=<optimized out>) at client/advertising.c:253
>>
>> After Fix:
>> [bluetooth]# set-advertise-name Test
>> [bluetooth]# set-advertise-uuids 0x1824
>> [bluetooth]# set-advertise-manufacturer 0x75 0x02 0x03 0x04
>> [bluetooth]# advertise on
>> [CHG] Controller 00:19:0E:11:55:44 SupportedInstances: 0x04
>> [CHG] Controller 00:19:0E:11:55:44 ActiveInstances: 0x01
>> Advertising object registered
>> [bluetooth]#
>> ---
>>  client/advertising.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/client/advertising.c b/client/advertising.c
>> index 76cee3d..7d98ae3 100644
>> --- a/client/advertising.c
>> +++ b/client/advertising.c
>> @@ -175,7 +175,7 @@ static void append_array_variant(DBusMessageIter *iter, int type, void *val,
>>                                                 type_sig, &array);
>>
>>         if (dbus_type_is_fixed(type) == TRUE) {
>> -               dbus_message_iter_append_fixed_array(&array, type, val,
>> +               dbus_message_iter_append_fixed_array(&array, type, &val,
>>                                                         n_elements);
>>         } else if (type == DBUS_TYPE_STRING || type == DBUS_TYPE_OBJECT_PATH) {
>>                 const char ***str_array = val;
>> --
>> 1.9.1
>
> Thanks for the patch but the proper fix is to call dict_append_array
> with correct pointer otherwise this API will not be consistent with
> libdbus, so we may want to have pointer to &ad->data and then pass its
> address there.

I went ahead and made the changes suggested above and applied it.
Thanks for the patch.

-- 
Luiz Augusto von Dentz