[libvirt] [PATCH 1/6] virNetDevBridgeGet: Avoid NULL dereference

[Peter Krempa]

On Tue, May 31, 2016 at 13:17:30 +0200, Michal Privoznik wrote:
> On 31.05.2016 13:06, Peter Krempa wrote:
> > On Tue, May 31, 2016 at 12:33:25 +0200, Michal Privoznik wrote:
> >> It may happen, that this function would dereference a NULL
> >> pointer:
> >>
> >> util/virnetdevbridge.c: In function 'virNetDevBridgeGetVlanFiltering':
> >> util/virnetdevbridge.c:199:23: error: null pointer dereference [-Werror=null-dereference]
> >>          ifr->ifr_data = (char*)&args;
> >>          ~~~~~~~~~~~~~~^~~~~~~~~~~~~~
> >>
> >> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> >> ---
> >>  src/util/virnetdevbridge.c | 6 +++++-
> >>  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > How about fixing the single caller that passes NULL in @ifr?
> > 
> > virNetDevBridgeGetVlanFiltering
> > 
> 
> What about it? AFAIK, SIOCDEVPRIVATE ioctl is not able to tell us
> whether vlan filtering is enabled. Therefore I don't see much sense in
> providing a fd and ifreq struct just so that we can go through else
> branch too.

Then the check should be based on @fd being -1 where apparently the
second case doesn't make sense at all whether @ifr is set or not.

I think it would make sense to extract the part that operates on @path
and call it separately since you don't need the fallback path at all
rather than using the compound function.
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