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Mon, 20 Apr 2026 08:42:24 -0700 (PDT) Date: Mon, 20 Apr 2026 08:42:23 -0700 From: Stanislav Fomichev To: Jason Xing Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, bjorn@kernel.org, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com, sdf@fomichev.me, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, horms@kernel.org, andrew+netdev@lunn.ch, bpf@vger.kernel.org, netdev@vger.kernel.org, Jason Xing Subject: Re: [PATCH net 1/4] xsk: avoid skb leak in XDP_TX_METADATA case Message-ID: References: <20260418045644.28612-1-kerneljasonxing@gmail.com> <20260418045644.28612-2-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On 04/20, Stanislav Fomichev wrote: > On 04/18, Jason Xing wrote: > > From: Jason Xing > > > > Fix it by explicitly adding kfree_skb() before returning back to its > > caller. > > > > How to reproduce it in virtio_net: > > 1. the current skb is the first one (which means no frag and xs->skb is > > NULL) and users enable metadata feature. > > 2. xsk_skb_metadata() returns a error code. > > 3. the caller xsk_build_skb() clears skb by using 'skb = NULL;'. > > 4. there is no chance to free this skb anymore. > > > > Closes: https://lore.kernel.org/all/20260415085204.3F87AC19424@smtp.kernel.org/ > > Fixes: 30c3055f9c0d ("xsk: wrap generic metadata handling onto separate function") > > Signed-off-by: Jason Xing > > Acked-by: Stanislav Fomichev Actually, I take that back.. While looking at patch 2 (which always confuses me with that -EOVERFLOW handling), looks like we set skb->destructor in xsk_skb_init_misc? So this kfree will do xsk_cq_submit_addr_locked? Not sure that's what we want? Should we move xsk_skb_init_misc to happen after xsk_skb_metadata?