Re: [PATCH mptcp-stable] mptcp: fix msk traversal in mptcp_nl_cmd_set_flags()

[Greg KH <greg@kroah.com>]

On Tue, Feb 01, 2022 at 05:09:36PM -0800, Mat Martineau wrote:
> On Tue, 1 Feb 2022, Mat Martineau wrote:
> 
> > commit 8e9eacad7ec7a9cbf262649ebf1fa6e6f6cc7d82 upstream.
> > 
> > The upstream commit had to handle a lookup_by_id variable that is only
> > present in 5.17. This version of the patch removes that variable, so the
> > __lookup_addr() function only handles the lookup as it is implemented in
> > 5.15 and 5.16. It also removes one 'const' keyword to prevent a warning
> > due to differing const-ness in the 5.17 version of addresses_equal().
> > 
> > The MPTCP endpoint list is under RCU protection, guarded by the
> > pernet spinlock. mptcp_nl_cmd_set_flags() traverses the list
> > without acquiring the spin-lock nor under the RCU critical section.
> > 
> > This change addresses the issue performing the lookup and the endpoint
> > update under the pernet spinlock.
> > 
> > Fixes: 0f9f696a502e ("mptcp: add set_flags command in PM netlink")
> > Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
> > ---
> > 
> > Paolo, can I add an ack or signoff tag from you?
> > 
> > The upstream commit (8e9eacad7ec7) was queued for the 5.16 and 5.15
> > stable trees, which brought along a few extra patches that didn't belong
> > in stable. I asked Greg to drop those patches from his queue, and this
> > particular commit required manual changes as described above (related to
> > the lookup_by_id variable that's new in 5.16).
> > 
> > This patch will not apply to the export branch. I confirmed that it
> > applies, builds, and runs on both the 5.16.5 and 5.15.19 branches. Self
> > tests succeed too.
> > 
> > When I send to the stable list, I'll also include these tags:
> > Cc: <stable@vger.kernel.org> # 5.15.x
> > Cc: <stable@vger.kernel.org> # 5.16.x
> 
> So... this wasn't supposed to go to stable@vger.kernel.org yet. git
> send-email picked up the cc lines that I had moved out of the commit
> message. Sorry about that.

There's nothing wrong with us seeing it as kernel development should be
done in public :)

thanks,

greg k-h