From: Zhao Zhang Devmap broadcast redirects clone the packet for all but the last destination. For native XDP, that clone path copies only the linear xdp_frame data, while fragmented frames keep skb_shared_info in tailroom outside the linear area. Cloning such a frame leaves XDP_FLAGS_HAS_FRAGS set but without valid frag metadata, and the later free path can interpret uninitialized tail data as skb_shared_info, leading to an out-of-bounds access during frame return. Reject fragmented native XDP frames in dev_map_enqueue_clone(). Add the same restriction to the generic XDP clone path in dev_map_redirect_clone(). Generic XDP represents fragmented packets as nonlinear skbs, and rejecting them here keeps clone-based broadcast support aligned between native and generic XDP. Fixes: e624d4ed4aa8 ("xdp: Extend xdp_redirect_map with broadcast support") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Zhengchuan Liang Reported-by: Xin Liu Assisted-by: Codex:GPT-5.4 Signed-off-by: Zhao Zhang Signed-off-by: Ren Wei --- changes in v2: - Add the same fragmented-packet restriction to generic XDP dev_map_redirect_clone() so clone-based broadcast behavior stays aligned with the native XDP path. - v1 link: https://lore.kernel.org/all/4b596825bccc64d03e0c2e0db4dceb12c7f5cf47.1780176829.git.zzhan461@ucr.edu/ kernel/bpf/devmap.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index cc0a43ebab6b..5b9eac5342a9 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -581,6 +581,10 @@ static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj, { struct xdp_frame *nxdpf; + /* Frags live outside the linear frame and cannot be cloned safely. */ + if (unlikely(xdp_frame_has_frags(xdpf))) + return -EOPNOTSUPP; + nxdpf = xdpf_clone(xdpf); if (!nxdpf) return -ENOMEM; @@ -726,6 +730,9 @@ static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst, struct sk_buff *nskb; int err; + if (unlikely(skb_is_nonlinear(skb))) + return -EOPNOTSUPP; + nskb = skb_clone(skb, GFP_ATOMIC); if (!nskb) return -ENOMEM; -- 2.47.3