Re: [PATCH net] ipv6: fix src addr routing with the exception table

[Martin Lau <kafai@fb.com>]

On Wed, May 15, 2019 at 06:06:58PM -0600, David Ahern wrote:
> On 5/15/19 6:03 PM, Wei Wang wrote:
> > Thanks Martin.
> > Changing __rt6_find_exception_xxx() might not be easy cause other
> > callers of this function does not really need to back off and use
> > another saddr.
> > And the validation of the result is a bit different for different callers.
I was thinking other callers can pass NULL for the new arg "saddr2".

> > What about add a new helper for the above 2 cases and just call that
> > from both places?
That will also do.  I think it may even have less code churn
on the existing functions.  I guess the new helper may just call
__rt6_find_exception_rcu() inside with "saddr" first and
then again with "saddr2" (if needed)?

> 
> Since this needs to be backported to stable releases, I would say
> simplest patch for that is best.
> 
> I have changes queued for this area once net-next opens; I can look at
> consolidating as part of that.
Some of the functions have mutliple changes since then, I suspect
less code churn on these existing functions will make the backport
to stable easier also.
This bug has been there since 4.15.  I think it can take a mement
to do it now rather than later.