Re: [Qemu-devel] [PATCH] hw/9pfs/virtio-9p-proxy: Fix possible overflow

[Shannon Zhao <zhaoshenglong@huawei.com>]

On 2015/3/16 15:58, Aneesh Kumar K.V wrote:
> Shannon Zhao <zhaoshenglong@huawei.com> writes:
> 
>> It's detected by coverity. As max of sockaddr_un.sun_path is
>> sizeof(helper.sun_path), should check the length of source
>> and use strncpy instead of strcpy.
>>
>> Signed-off-by: Shannon Zhao <zhaoshenglong@huawei.com>
>> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
>> ---
>>  hw/9pfs/virtio-9p-proxy.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/9pfs/virtio-9p-proxy.c b/hw/9pfs/virtio-9p-proxy.c
>> index 59c7445..fb1ab7b 100644
>> --- a/hw/9pfs/virtio-9p-proxy.c
>> +++ b/hw/9pfs/virtio-9p-proxy.c
>> @@ -1102,12 +1102,13 @@ static int connect_namedsocket(const char *path)
>>      int sockfd, size;
>>      struct sockaddr_un helper;
>>  
>> +    g_assert(strlen(path) < sizeof(helper.sun_path));
> 
> Since we are doing this from within Qemu, I did the below and folded
> that into other sockadd_un.sun_path size checking patch.
> 
> diff --git a/hw/9pfs/virtio-9p-proxy.c b/hw/9pfs/virtio-9p-proxy.c
> index 6bb191ee6ab8..71b6198bbd22 100644
> --- a/hw/9pfs/virtio-9p-proxy.c
> +++ b/hw/9pfs/virtio-9p-proxy.c
> @@ -1100,6 +1100,10 @@ static int connect_namedsocket(const char *path)
>      int sockfd, size;
>      struct sockaddr_un helper;
>  
> +    if (strlen(path) >= sizeof(helper.sun_path)) {
> +        fprintf(stderr, "Socket name too large\n");
> +        return -1;
> +    }
>      sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
>      if (sockfd < 0) {
>          fprintf(stderr, "failed to create socket: %s\n", strerror(errno));
> 
> 
> Let me know if that is ok for you.
> 

That's OK. :-)

-- 
Thanks,
Shannon

>>      sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
>>      if (sockfd < 0) {
>>          fprintf(stderr, "failed to create socket: %s\n", strerror(errno));
>>          return -1;
>>      }
>> -    strcpy(helper.sun_path, path);
>> +    strncpy(helper.sun_path, path, sizeof(helper.sun_path));
>>      helper.sun_family = AF_UNIX;
>>      size = strlen(helper.sun_path) + sizeof(helper.sun_family);
>>      if (connect(sockfd, (struct sockaddr *)&helper, size) < 0) {
>> -- 
>> 1.8.3.1
> 
> 
> .
>