kernel/linux.git/net/xdp, branch v6.6.142

xsk: validate MTU against usable frame size on bind

2026-04-27T13:23:28+00:00

[ Upstream commit 36ee60b569ba0dfb6f961333b90d19ab5b323fa9 ] AF_XDP bind currently accepts zero-copy pool configurations without verifying that the device MTU fits into the usable frame space provided by the UMEM chunk. This becomes a problem since we started to respect tailroom which is subtracted from chunk_size (among with headroom). 2k chunk size might not provide enough space for standard 1500 MTU, so let us catch such settings at bind time. Furthermore, validate whether underlying HW will be able to satisfy configured MTU wrt XSK's frame size multiplied by supported Rx buffer chain length (that is exposed via net_device::xdp_zc_max_segs). Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX") Reviewed-by: Björn Töpel Signed-off-by: Maciej Fijalkowski Link: https://patch.msgid.link/20260402154958.562179-5-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

xsk: fix XDP_UMEM_SG_FLAG issues

2026-04-27T13:23:28+00:00

[ Upstream commit 93e84fe45b752d17a5a46b306ed78f0133bbc719 ] Currently xp_assign_dev_shared() is missing XDP_USE_SG being propagated to flags so set it in order to preserve mtu check that is supposed to be done only when no multi-buffer setup is in picture. Also, this flag has the same value as XDP_UMEM_TX_SW_CSUM so we could get unexpected SG setups for software Tx checksums. Since csum flag is UAPI, modify value of XDP_UMEM_SG_FLAG. Fixes: d609f3d228a8 ("xsk: add multi-buffer support for sockets sharing umem") Reviewed-by: Björn Töpel Signed-off-by: Maciej Fijalkowski Link: https://patch.msgid.link/20260402154958.562179-4-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

xsk: respect tailroom for ZC setups

2026-04-27T13:23:28+00:00

[ Upstream commit 1ee1605138fc94cc8f8f273321dd2471c64977f9 ] Multi-buffer XDP stores information about frags in skb_shared_info that sits at the tailroom of a packet. The storage space is reserved via xdp_data_hard_end(): ((xdp)->data_hard_start + (xdp)->frame_sz - \ SKB_DATA_ALIGN(sizeof(struct skb_shared_info))) and then we refer to it via macro below: static inline struct skb_shared_info * xdp_get_shared_info_from_buff(const struct xdp_buff *xdp) { return (struct skb_shared_info *)xdp_data_hard_end(xdp); } Currently we do not respect this tailroom space in multi-buffer AF_XDP ZC scenario. To address this, introduce xsk_pool_get_tailroom() and use it within xsk_pool_get_rx_frame_size() which is used in ZC drivers to configure length of HW Rx buffer. Typically drivers on Rx Hw buffers side work on 128 byte alignment so let us align the value returned by xsk_pool_get_rx_frame_size() in order to avoid addressing this on driver's side. This addresses the fact that idpf uses mentioned function *before* pool->dev being set so we were at risk that after subtracting tailroom we would not provide 128-byte aligned value to HW. Since xsk_pool_get_rx_frame_size() is actively used in xsk_rcv_check() and __xsk_rcv(), add a variant of this routine that will not include 128 byte alignment and therefore old behavior is preserved. Reviewed-by: Björn Töpel Acked-by: Stanislav Fomichev Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX") Signed-off-by: Maciej Fijalkowski Link: https://patch.msgid.link/20260402154958.562179-3-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

xsk: tighten UMEM headroom validation to account for tailroom and min frame

2026-04-27T13:23:28+00:00

[ Upstream commit a315e022a72d95ef5f1d4e58e903cb492b0ad931 ] The current headroom validation in xdp_umem_reg() could leave us with insufficient space dedicated to even receive minimum-sized ethernet frame. Furthermore if multi-buffer would come to play then skb_shared_info stored at the end of XSK frame would be corrupted. HW typically works with 128-aligned sizes so let us provide this value as bare minimum. Multi-buffer setting is known later in the configuration process so besides accounting for 128 bytes, let us also take care of tailroom space upfront. Reviewed-by: Björn Töpel Acked-by: Stanislav Fomichev Fixes: 99e3a236dd43 ("xsk: Add missing check on user supplied headroom size") Signed-off-by: Maciej Fijalkowski Link: https://patch.msgid.link/20260402154958.562179-2-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

xsk: Fix zero-copy AF_XDP fragment drop

2026-03-25T10:05:39+00:00

[ Upstream commit f7387d6579d65efd490a864254101cb665f2e7a7 ] AF_XDP should ensure that only a complete packet is sent to application. In the zero-copy case, if the Rx queue gets full as fragments are being enqueued, the remaining fragments are dropped. For the multi-buffer case, add a check to ensure that the Rx queue has enough space for all fragments of a packet before starting to enqueue them. Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX") Signed-off-by: Nikhil P. Rao Link: https://patch.msgid.link/20260225000456.107806-3-nikhil.rao@amd.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

xsk: Fix fragment node deletion to prevent buffer leak

2026-03-25T10:05:39+00:00

[ Upstream commit 60abb0ac11dccd6b98fd9182bc5f85b621688861 ] After commit b692bf9a7543 ("xsk: Get rid of xdp_buff_xsk::xskb_list_node"), the list_node field is reused for both the xskb pool list and the buffer free list, this causes a buffer leak as described below. xp_free() checks if a buffer is already on the free list using list_empty(&xskb->list_node). When list_del() is used to remove a node from the xskb pool list, it doesn't reinitialize the node pointers. This means list_empty() will return false even after the node has been removed, causing xp_free() to incorrectly skip adding the buffer to the free list. Fix this by using list_del_init() instead of list_del() in all fragment handling paths, this ensures the list node is reinitialized after removal, allowing the list_empty() to work correctly. Fixes: b692bf9a7543 ("xsk: Get rid of xdp_buff_xsk::xskb_list_node") Acked-by: Maciej Fijalkowski Signed-off-by: Nikhil P. Rao Link: https://patch.msgid.link/20260225000456.107806-2-nikhil.rao@amd.com Signed-off-by: Jakub Kicinski Stable-dep-of: f7387d6579d6 ("xsk: Fix zero-copy AF_XDP fragment drop") Signed-off-by: Sasha Levin

xsk: s/free_list_node/list_node/

2026-03-25T10:05:39+00:00

[ Upstream commit 30ec2c1baaead43903ad63ff8e3083949059083c ] Now that free_list_node's purpose is two-folded, make it just a 'list_node'. Signed-off-by: Maciej Fijalkowski Signed-off-by: Daniel Borkmann Acked-by: Magnus Karlsson Link: https://lore.kernel.org/bpf/20241007122458.282590-3-maciej.fijalkowski@intel.com Stable-dep-of: f7387d6579d6 ("xsk: Fix zero-copy AF_XDP fragment drop") Signed-off-by: Sasha Levin

xsk: Get rid of xdp_buff_xsk::xskb_list_node

2026-03-25T10:05:39+00:00

[ Upstream commit b692bf9a7543af7ad11a59d182a3757578f0ba53 ] Let's bring xdp_buff_xsk back to occupying 2 cachelines by removing xskb_list_node - for the purpose of gathering the xskb frags free_list_node can be used, head of the list (xsk_buff_pool::xskb_list) stays as-is, just reuse the node ptr. It is safe to do as a single xdp_buff_xsk can never reside in two pool's lists simultaneously. Signed-off-by: Maciej Fijalkowski Signed-off-by: Daniel Borkmann Acked-by: Magnus Karlsson Link: https://lore.kernel.org/bpf/20241007122458.282590-2-maciej.fijalkowski@intel.com Stable-dep-of: f7387d6579d6 ("xsk: Fix zero-copy AF_XDP fragment drop") Signed-off-by: Sasha Levin

xsk: Fix race condition in AF_XDP generic RX path

2026-02-06T15:48:29+00:00

[ Upstream commit a1356ac7749cafc4e27aa62c0c4604b5dca4983e ] Move rx_lock from xsk_socket to xsk_buff_pool. Fix synchronization for shared umem mode in generic RX path where multiple sockets share single xsk_buff_pool. RX queue is exclusive to xsk_socket, while FILL queue can be shared between multiple sockets. This could result in race condition where two CPU cores access RX path of two different sockets sharing the same umem. Protect both queues by acquiring spinlock in shared xsk_buff_pool. Lock contention may be minimized in the future by some per-thread FQ buffering. It's safe and necessary to move spin_lock_bh(rx_lock) after xsk_rcv_check(): * xs->pool and spinlock_init is synchronized by xsk_bind() -> xsk_is_bound() memory barriers. * xsk_rcv_check() may return true at the moment of xsk_release() or xsk_unbind_dev(), however this will not cause any data races or race conditions. xsk_unbind_dev() removes xdp socket from all maps and waits for completion of all outstanding rx operations. Packets in RX path will either complete safely or drop. Signed-off-by: Eryk Kubanski Fixes: bf0bdd1343efb ("xdp: fix race on generic receive path") Acked-by: Magnus Karlsson Link: https://patch.msgid.link/20250416101908.10919-1-e.kubanski@partner.samsung.com Signed-off-by: Jakub Kicinski [ Conflict is resolved when backporting this fix. ] Signed-off-by: Jianqiang kang Signed-off-by: Greg Kroah-Hartman

xsk: fix an integer overflow in xp_create_and_assign_umem()

2025-03-28T20:59:55+00:00

commit 559847f56769037e5b2e0474d3dbff985b98083d upstream. Since the i and pool->chunk_size variables are of type 'u32', their product can wrap around and then be cast to 'u64'. This can lead to two different XDP buffers pointing to the same memory area. Found by InfoTeCS on behalf of Linux Verification Center (linuxtesting.org) with SVACE. Fixes: 94033cd8e73b ("xsk: Optimize for aligned case") Cc: stable@vger.kernel.org Signed-off-by: Ilia Gavrilov Link: https://patch.msgid.link/20250313085007.3116044-1-Ilia.Gavrilov@infotecs.ru Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman