From: Linpu Yu Date: Fri, 8 May 2026 14:43:43 +0000 (+0800) Subject: xskmap: reject TX-only AF_XDP sockets X-Git-Tag: v7.1-rc3~4^2~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bf6d507f7e3c65751d52fd8caf1ea4e003922624;p=thirdparty%2Fkernel%2Fstable.git xskmap: reject TX-only AF_XDP sockets 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 Reviewed-by: Jason Xing Link: https://lore.kernel.org/r/20260508144344.694-1-linpu5433@gmail.com Signed-off-by: Alexei Starovoitov --- 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);