[PATCH] virMacAddrParse: Fix wrong termination character

[Eustance Wu]

Thanks a lot.

In libvirt of the latest code of the current master: When configuring the
mac address of the DHCP host (c0:3b:04:21:15:35), if a space is added at
the end (c0:3b:04:21:15:35\32 ), no error is thrown when starting the
network.
I think an error should be thrown because such a mac (c0:3b:04:21:15:35\32)
is not legal
And the mac address (c0:3b:04:21:15:35) does not take effect
The diagram is as follows:
[image: image.png]

> >*          addr->addr[i] = (unsigned char) result;
*> >* -        if ((i == 5) && (*end_ptr <= ' '))
*>* +        if ((i == 5) && (*end_ptr == '\0'))
*



Can I mention a patch for this issue?
Will this affect other functions?


Peter Krempa <pkrempa at redhat.com> 于2022年6月16日周四 14:52写道：

> On Thu, Jun 16, 2022 at 14:09:06 +0800, Eustance Wu wrote:
> > From ef22e53c9360ddb4bdff61a12013a2812fb7346a Mon Sep 17 00:00:00 2001
> > From: longtao <longtao.wu at zstack.io>
> > Date: Thu, 16 Jun 2022 14:08:14 +0800
> > Subject: [PATCH] virMacAddrParse: Fix wrong termination character
> >
> > The judgment of the termination character should be the '\0' character,
> not
> > a space.
> > Using spaces to judge, content can be injected into mac. such as:
> > "70:af:e7:1f:3f:89\32injected".
> >
> > Before this patch, the terminating character was a space ('\32'),not
> '\0'.
>
> This sentence is inaccurate, it was any byte between 0 and ' '.
>
> > So I can set the DHCP host mac like this "<host mac='c0:3b:04:21:15:35
> >  injected' name='name129' ip='192.168.100.129'/>".
>
> This format does not conform to our XML schema. The 'mac' attribute is
> defined as:
>
>   <define name="uniMacAddr">
>     <data type="string">
>       <param
> name="pattern">[a-fA-F0-9][02468aAcCeE](:[a-fA-F0-9]{2}){5}</param>
>     </data>
>   </define>
>
> Thus 'space' or any other character is _not_ allowed in int including
> the word 'injected'.
>
> What are you actually trying to achieve? This is not clear from the
> description in this bug.
>
> Please describe also the end goal ...
>
> > When running the network, no error is reported.
> > But, when using this mac to create a virtual machine,  Will get
> > "virNetSocketReadWire:1805 : End of file while reading data: Input/output
>
> ... rather than just an error you are seeing, since this doesn't seem to
> be a plain bugfix.
>
> > error" in the libvirtd log.
> > ---
> >  src/util/virmacaddr.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/src/util/virmacaddr.c b/src/util/virmacaddr.c
> > index 6b22384cee..ba7c7e7076 100644
> > --- a/src/util/virmacaddr.c
> > +++ b/src/util/virmacaddr.c
> > @@ -163,7 +163,7 @@ virMacAddrParse(const char* str, virMacAddr *addr)
>
> This helper is used in many places, outside of the network driver, so
> this will need careful assesment whether any other code depends on the
> old behaviour.
>
> >
> >          addr->addr[i] = (unsigned char) result;
> >
> > -        if ((i == 5) && (*end_ptr <= ' '))
> > +        if ((i == 5) && (*end_ptr == 0))
>
> We prefer to use the character literal version of the nul byte ('\0').
>
> >              return 0;
> >          if (*end_ptr != ':')
> >              break;
> > --
> > 2.32.0
>
>
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