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Sat, 08 Mar 2025 09:08:54 -0800 (PST) Received: from localhost ([2601:646:9e00:f56e:2844:3d8f:bf3e:12cc]) by smtp.gmail.com with UTF8SMTPSA id d9443c01a7336-22410a7fa3csm48879285ad.110.2025.03.08.09.08.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Mar 2025 09:08:53 -0800 (PST) Date: Sat, 8 Mar 2025 09:08:52 -0800 From: Stanislav Fomichev To: Eric Dumazet Cc: Stanislav Fomichev , netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, horms@kernel.org, corbet@lwn.net, andrew+netdev@lunn.ch, pablo@netfilter.org, kadlec@netfilter.org Subject: Re: [PATCH net-next] net: revert to lockless TC_SETUP_BLOCK and TC_SETUP_FT Message-ID: References: <20250308044726.1193222-1-sdf@fomichev.me> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On 03/08, Eric Dumazet wrote: > On Sat, Mar 8, 2025 at 5:47 AM Stanislav Fomichev wrote: > > > > There is a couple of places from which we can arrive to ndo_setup_tc > > with TC_SETUP_BLOCK/TC_SETUP_FT: > > - netlink > > - netlink notifier > > - netdev notifier > > > > Locking netdev too deep in this call chain seems to be problematic > > (especially assuming some/all of the call_netdevice_notifiers > > NETDEV_UNREGISTER) might soon be running with the instance lock). > > Revert to lockless ndo_setup_tc for TC_SETUP_BLOCK/TC_SETUP_FT. NFT > > framework already takes care of most of the locking. Document > > the assumptions. > > > > > > > > Fixes: c4f0f30b424e ("net: hold netdev instance lock during nft ndo_setup_tc") > > Signed-off-by: Stanislav Fomichev > > I think you forgot to mention syzbot. > > Reported-by: syzbot+0afb4bcf91e5a1afdcad@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/67cb88d1.050a0220.d8275.022d.GAE@google.com/T/#u Ah, yes, I was waiting for a repro, but should have attached the proper tags, thanks!