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

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

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.
         
>      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