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Re: [Qemu-devel] [PATCH] vl.c: fix memleaks with g_strdup+strtok
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH] vl.c: fix memleaks with g_strdup+strtok |
Date: |
Wed, 2 Mar 2016 11:13:36 +0000 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Wed, Mar 02, 2016 at 11:07:02AM +0000, Stefan Hajnoczi wrote:
> 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.
If fixing it I'd probably suggest using g_strsplit() instead of
strdup+strtok too, as it accepts a const string & returns allocated
strings which is a nicer contract that strtok which modifies its arg
Regards,
Daniel
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