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Sat, 02 May 2026 13:07:45 -0700 (PDT) Received: from KERNELXING-MC1.tencent.com ([41.128.91.35]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-67b88094aa4sm1902528a12.24.2026.05.02.13.07.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 May 2026 13:07:44 -0700 (PDT) From: Jason Xing To: 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 Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, Jason Xing Subject: [PATCH net v5 6/8] xsk: avoid skb leak in XDP_TX_METADATA case Date: Sat, 2 May 2026 23:07:20 +0300 Message-Id: <20260502200722.53960-7-kerneljasonxing@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20260502200722.53960-1-kerneljasonxing@gmail.com> References: <20260502200722.53960-1-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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") Acked-by: Stanislav Fomichev Signed-off-by: Jason Xing --- net/xdp/xsk.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 13bacc11fa9d..5e6326e076ab 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -741,8 +741,10 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, skb_reserve(skb, hr); if (desc->options & XDP_TX_METADATA) { err = xsk_skb_metadata(skb, buffer, desc, pool, hr); - if (unlikely(err)) + if (unlikely(err)) { + kfree_skb(skb); return ERR_PTR(err); + } } } else { struct xsk_addrs *xsk_addr; -- 2.41.3