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Tue, 28 Apr 2026 05:55:39 -0700 (PDT) From: Linpu Yu To: kerneljasonxing@gmail.com, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, netdev@vger.kernel.org, bpf@vger.kernel.org Cc: sdf@fomichev.me, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, bjorn@kernel.org, linux-kernel@vger.kernel.org, tanyuan98@outlook.com, yifanwucs@gmail.com Subject: [PATCH bpf-next v3] xskmap: reject TX-only AF_XDP sockets Date: Tue, 28 Apr 2026 20:54:58 +0800 Message-ID: <20260428125518.4556-1-linpu5433@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <2b156bc4277a9e891f3399935416701d1f9efd7c.1777276241.git.linpu5433@gmail.com> References: <2b156bc4277a9e891f3399935416701d1f9efd7c.1777276241.git.linpu5433@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit XSKMAP entries are used as redirect targets for incoming XDP frames. A TX-only AF_XDP socket lacks an Rx ring and cannot handle redirected traffic, but xsk_map_update_elem() currently allows such sockets to be inserted into the map. Redirecting packets to such a socket on the veth generic-XDP path causes a kernel crash in xsk_generic_rcv(). This became possible after xsk_is_setup_for_bpf_map() was removed from the XSKMAP update path, which allowed bound TX-only sockets to be inserted into the map. Reject TX-only sockets during XSKMAP updates to avoid the crash. They remain fully operational for pure Tx purposes outside XSKMAP. Fixes: 968be23ceaca ("xsk: Fix possible segfault at xskmap entry insertion") Reported-by: Juefei Pu Reported-by: Yuan Tan Reported-by: Xin Liu Signed-off-by: Yifan Wu Signed-off-by: Linpu Yu --- Changes in v3: - fix the Fixes tag to point to 968be23ceaca net/xdp/xskmap.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/xdp/xskmap.c b/net/xdp/xskmap.c index afa457506274..3bff346308d0 100644 --- a/net/xdp/xskmap.c +++ b/net/xdp/xskmap.c @@ -184,6 +184,10 @@ static long xsk_map_update_elem(struct bpf_map *map, void *key, void *value, } xs = (struct xdp_sock *)sock->sk; + if (!READ_ONCE(xs->rx)) { + sockfd_put(sock); + return -ENOBUFS; + } map_entry = &m->xsk_map[i]; node = xsk_map_node_alloc(m, map_entry); -- 2.54.0