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Re: [libvirt] [PATCH] Sanitize qemu monitor reads



On Tue, Sep 23, 2008 at 04:56:08PM -0400, Cole Robinson wrote:
> @@ -1670,7 +1670,7 @@ qemudMonitorCommand (const struct qemud_driver *driver ATTRIBUTE_UNUSED,
>                       const char *cmd,
>                       char **reply) {
>      int size = 0;
> -    char *buf = NULL;
> +    char *buf = NULL, *tmpbuf = NULL, *nlptr = NULL, *commptr = NULL;
>      size_t cmdlen = strlen(cmd);
>  
>      if (safewrite(vm->monitor, cmd, cmdlen) != cmdlen)
> @@ -1708,7 +1708,31 @@ qemudMonitorCommand (const struct qemud_driver *driver ATTRIBUTE_UNUSED,
>  
>          /* Look for QEMU prompt to indicate completion */
>          if (buf && ((tmp = strstr(buf, "\n(qemu) ")) != NULL)) {
> -            tmp[0] = '\0';
> +            /* Preserve the newline */
> +            tmp[1] = '\0';
> +
> +            /* The monitor doesn't dump clean output after we have written to
> +             * it. Every character we write dumps a bunch of useless stuff,
> +             * so the result looks like "cXcoXcomXcommXcommaXcommanXcommand"
> +             * Try to throw away everything before the first full command
> +             * occurence, and inbetween the command and the newline starting
> +             * the response
> +             */
> +            if ((commptr = strstr(buf, cmd))) {
> +                tmpbuf = buf;
> +                buf = NULL;
> +                if ((nlptr = strchr(commptr, '\n'))) {
> +                    if (VIR_ALLOC_N(buf, strlen(cmd) + strlen(nlptr) + 1) < 0)
> +                        goto error;
> +                    strncpy(buf, cmd, strlen(cmd));
> +                    strcat(buf, nlptr);
> +                } else {
> +                    if ((buf = strdup(commptr)) == NULL)
> +                        goto error;
> +                }
> +                VIR_FREE(tmpbuf);
> +            }

It looks to me like tmpbuf is leaked on the two error paths.

garbage.collection++

Rich.

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v


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