Re: [Qemu-devel] [PATCH] vl.c: fix memleaks with g_strdup+strtok

[Stefan Hajnoczi]

On Wed, Feb 24, 2016 at 10:22:14AM +0100, Quentin PEREZ wrote:
> diff --git a/vl.c b/vl.c
> index b87e292..9f6593a 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1362,16 +1362,19 @@ static int add_semihosting_arg(void *opaque,
>  static inline void semihosting_arg_fallback(const char *file, const char 
> *cmd)
>  {
>      char *cmd_token;
> +    char *dup_cmd;
> 
>      /* argv[0] */
>      add_semihosting_arg(&semihosting, "arg", file, NULL);
> 
>      /* split -append and initialize argv[1..n] */
> -    cmd_token = strtok(g_strdup(cmd), " ");
> +    dup_cmd = g_strdup(cmd);
> +    cmd_token = strtok(dup_cmd, " ");
>      while (cmd_token) {
>          add_semihosting_arg(&semihosting, "arg", cmd_token, NULL);
>          cmd_token = strtok(NULL, " ");
>      }
> +    g_free(dup_cmd);

add_semihosting_arg() stashes the cmd_token pointer.  semihosting.argv[]
points to freed memory if you add g_free(dup_cmd).

I suggest leaving the code as-is since the lifetime of the semihosting
global variable spans the entire run-time of the QEMU process.  It's not
pretty but the leak is harmless.

If you really want to fix it you may need to add a semihosting_cleanup()
function to free strings.

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