Re: [PATCH] 9p: fix NULL pointer dereferences

From: Dmitry Vyukov
Date: Wed Aug 08 2018 - 11:51:59 EST

On Fri, Jul 27, 2018 at 12:15 AM, Dominique Martinet
<asmadeus@xxxxxxxxxxxxx> wrote:
> Tomas Bortoli wrote on Thu, Jul 26, 2018:
>> > If we want to preserve the current behaviour for trans=fd (and I don't
>> > see why not) we just have to patch all the transports that use the
>> > device, that is all .create functions but p9_fd_create()
>> >
>> > Basically exactly what you did, just for a few more functions - I
>> > apparently was a little bit too optimistic thinking we could share
>> > this check.
>> Does v9fs_mount() knows the transport ahead? Because in that case it'd
>> be possible to check if addr!=NULL && trans!=fd then return error
>> Otherwise, patching all the .create, ok.
> 9p option parsing is all over the place, split in fs/9p/v9fs,
> net/9p/client and net/9p/trans_*... Which is actually somewhat of a
> problem because that means we can't warn on unused option as each parser
> does not know the full subset of options used, so if someone makes a
> typo they're on their own to figure it out :/
> If you want to factor it in, v9fs_mount does not know which transport is
> used, but p9_client_create does know - although the functions/structs
> are all static so you need to check clnt->trans_mod->name with strcmp
> and I'm honestly not sure that's better than checking in each function..
> But, as usual I'm happy as long as it works, so pick your poison :)

So let's proceed with checking in each transport function?