[libvirt] [PATCH] qemu: Check for negative port values in network drive configuration

[Peter Krempa]

On Thu, Feb 19, 2015 at 16:28:44 -0700, Eric Blake wrote:
> On 02/19/2015 08:53 AM, Erik Skultety wrote:
> > We interpret port values as signed int (convert them from char *),
> > so if a negative value is provided in network disk's configuration,
> > we accept it as valid, however there's an 'unknown cause' error raised later.
> > This error is only accidental because we return the port value in the return code.
> > This patch adds just a minor tweak to the already existing check so we
> > reject negative values the same way as we reject non-numerical strings.
> > 
> > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1163553
> > ---
> >  src/qemu/qemu_command.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> > index 743d6f0..c1e9559 100644
> > --- a/src/qemu/qemu_command.c
> > +++ b/src/qemu/qemu_command.c
> > @@ -2954,7 +2954,7 @@ qemuNetworkDriveGetPort(int protocol,
> >      int ret = 0;
> >  
> >      if (port) {
> > -        if (virStrToLong_i(port, NULL, 10, &ret) < 0) {
> > +        if (virStrToLong_i(port, NULL, 10, &ret) < 0 || ret < 0) {
> >              virReportError(VIR_ERR_INTERNAL_ERROR,
> >                             _("failed to parse port number '%s'"),
> >                             port);
> 
> Won't this still allow wraparound (an extremely large negative input
> that gets parsed as positive)?  Wouldn't it be better to switch to
> virStrToLong_uip to force a positive number parse?

The wrap-around case should be handled fine with the existing helper for
signed numbers. Actually, when using virStrToLong_uip, we'd need to make
sure that the number won't get wrapped as the function is returning an
int due to error reporting.

I think Erik's patch is actually fine in the context of the code.

Peter

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