[PATCH] wayland-server: Fix null pointer dereferencing

[Marek Chalupa]

On 07/16/2015 09:22 AM, Giulio Camuffo wrote:
> 2015-07-16 9:27 GMT+03:00 Ashim <ashim.shah at samsung.com>:
>> Initialising 'wl_client *client = NULL' and checking 'resource' for NULL and returning if found.
>> This patch will avoid dereferencing of 'resource' if NULL
>
> I think in this case passing a NULL resource to
> wl_resource_post_error() is a programming mistake, and it should
> crash. If there is the possibility somewhere that the resource is null
> it should be checked before calling wl_resource_post_error(), imho.

Yep, agree. But in wayland-server.c on line 783 it is programming 
mistake that should be fixed :)

> --
> Giulio
>
>>
>> Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=91356
>>
>> Signed-off-by: Ashim <ashim.shah at samsung.com>
>> ---
>>   src/wayland-server.c |    7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/wayland-server.c b/src/wayland-server.c
>> index 0f04f66..2a0d19c 100644
>> --- a/src/wayland-server.c
>> +++ b/src/wayland-server.c
>> @@ -207,7 +207,7 @@ WL_EXPORT void
>>   wl_resource_post_error(struct wl_resource *resource,
>>                         uint32_t code, const char *msg, ...)
>>   {
>> -       struct wl_client *client = resource->client;
>> +       struct wl_client *client = NULL;
>>          char buffer[128];
>>          va_list ap;
>>
>> @@ -215,6 +215,11 @@ wl_resource_post_error(struct wl_resource *resource,
>>          vsnprintf(buffer, sizeof buffer, msg, ap);
>>          va_end(ap);
>>
>> +       if (resource == NULL)
>> +               return;
>> +       else
>> +               client = resource->client;
>> +
>>          client->error = 1;
>>
>>          /*
>> --
>> 1.7.9.5
>>
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