kernel/linux.git/drivers/net/virtio_net.c, branch v6.18.22

virtio_net: clamp rss_max_key_size to NETDEV_RSS_KEY_LEN

2026-04-11T12:26:46+00:00

commit b4e5f04c58a29c499faa85d12952ca9a4faf1cb9 upstream. rss_max_key_size in the virtio spec is the maximum key size supported by the device, not a mandatory size the driver must use. Also the value 40 is a spec minimum, not a spec maximum. The current code rejects RSS and can fail probe when the device reports a larger rss_max_key_size than the driver buffer limit. Instead, clamp the effective key length to min(device rss_max_key_size, NETDEV_RSS_KEY_LEN) and keep RSS enabled. This keeps probe working on devices that advertise larger maximum key sizes while respecting the netdev RSS key buffer size limit. Fixes: 3f7d9c1964fc ("virtio_net: Add hash_key_length check") Cc: stable@vger.kernel.org Signed-off-by: Srujana Challa Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/20260326142344.1171317-1-schalla@marvell.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false

2026-04-02T11:23:20+00:00

commit ba8bda9a0896746053aa97ac6c3e08168729172c upstream. A UAF issue occurs when the virtio_net driver is configured with napi_tx=N and the device's IFF_XMIT_DST_RELEASE flag is cleared (e.g., during the configuration of tc route filter rules). When IFF_XMIT_DST_RELEASE is removed from the net_device, the network stack expects the driver to hold the reference to skb->dst until the packet is fully transmitted and freed. In virtio_net with napi_tx=N, skbs may remain in the virtio transmit ring for an extended period. If the network namespace is destroyed while these skbs are still pending, the corresponding dst_ops structure has freed. When a subsequent packet is transmitted, free_old_xmit() is triggered to clean up old skbs. It then calls dst_release() on the skb associated with the stale dst_entry. Since the dst_ops (referenced by the dst_entry) has already been freed, a UAF kernel paging request occurs. fix it by adds skb_dst_drop(skb) in start_xmit to explicitly release the dst reference before the skb is queued in virtio_net. Call Trace: Unable to handle kernel paging request at virtual address ffff80007e150000 CPU: 2 UID: 0 PID: 6236 Comm: ping Kdump: loaded Not tainted 7.0.0-rc1+ #6 PREEMPT ... percpu_counter_add_batch+0x3c/0x158 lib/percpu_counter.c:98 (P) dst_release+0xe0/0x110 net/core/dst.c:177 skb_release_head_state+0xe8/0x108 net/core/skbuff.c:1177 sk_skb_reason_drop+0x54/0x2d8 net/core/skbuff.c:1255 dev_kfree_skb_any_reason+0x64/0x78 net/core/dev.c:3469 napi_consume_skb+0x1c4/0x3a0 net/core/skbuff.c:1527 __free_old_xmit+0x164/0x230 drivers/net/virtio_net.c:611 [virtio_net] free_old_xmit drivers/net/virtio_net.c:1081 [virtio_net] start_xmit+0x7c/0x530 drivers/net/virtio_net.c:3329 [virtio_net] ... Reproduction Steps: NETDEV="enp3s0" config_qdisc_route_filter() { tc qdisc del dev $NETDEV root tc qdisc add dev $NETDEV root handle 1: prio tc filter add dev $NETDEV parent 1:0 \ protocol ip prio 100 route to 100 flowid 1:1 ip route add 192.168.1.100/32 dev $NETDEV realm 100 } test_ns() { ip netns add testns ip link set $NETDEV netns testns ip netns exec testns ifconfig $NETDEV 10.0.32.46/24 ip netns exec testns ping -c 1 10.0.32.1 ip netns del testns } config_qdisc_route_filter test_ns sleep 2 test_ns Fixes: f2fc6a54585a ("[NETNS][IPV6] route6 - move ip6_dst_ops inside the network namespace") Cc: stable@vger.kernel.org Signed-off-by: xietangxin Reviewed-by: Xuan Zhuo Fixes: 0287587884b1 ("net: better IFF_XMIT_DST_RELEASE support") Link: https://patch.msgid.link/20260312025406.15641-1-xietangxin@yeah.net Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

virtio-net: correct hdr_len handling for VIRTIO_NET_F_GUEST_HDRLEN

2026-04-02T11:23:07+00:00

[ Upstream commit 38ec410b99a5ee6566f75650ce3d4fd632940fd0 ] The commit be50da3e9d4a ("net: virtio_net: implement exact header length guest feature") introduces support for the VIRTIO_NET_F_GUEST_HDRLEN feature in virtio-net. This feature requires virtio-net to set hdr_len to the actual header length of the packet when transmitting, the number of bytes from the start of the packet to the beginning of the transport-layer payload. However, in practice, hdr_len was being set using skb_headlen(skb), which is clearly incorrect. This commit fixes that issue. Fixes: be50da3e9d4a ("net: virtio_net: implement exact header length guest feature") Signed-off-by: Xuan Zhuo Link: https://patch.msgid.link/20260320021818.111741-2-xuanzhuo@linux.alibaba.com Acked-by: Michael S. Tsirkin Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

virtio-net: don't schedule delayed refill worker

2026-01-23T10:21:25+00:00

commit fcdef3bcbb2c04e06ae89f8faff2cd6416b3a467 upstream. When we fail to refill the receive buffers, we schedule a delayed worker to retry later. However, this worker creates some concurrency issues. For example, when the worker runs concurrently with virtnet_xdp_set, both need to temporarily disable queue's NAPI before enabling again. Without proper synchronization, a deadlock can happen when napi_disable() is called on an already disabled NAPI. That napi_disable() call will be stuck and so will the subsequent napi_enable() call. To simplify the logic and avoid further problems, we will instead retry refilling in the next NAPI poll. Fixes: 4bc12818b363 ("virtio-net: disable delayed refill when pausing rx") Reported-by: Paolo Abeni Closes: https://lore.kernel.org/526b5396-459d-4d02-8635-a222d07b46d7@redhat.com Cc: stable@vger.kernel.org Suggested-by: Xuan Zhuo Signed-off-by: Bui Quang Minh Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/20260106150438.7425-2-minhquangbui99@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

virtio_net: Fix misalignment bug in struct virtnet_info

2026-01-23T10:21:13+00:00

commit 4156c3745f06bc197094b9ee97a9584e69ed00bf upstream. Use the new TRAILING_OVERLAP() helper to fix a misalignment bug along with the following warning: drivers/net/virtio_net.c:429:46: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] This helper creates a union between a flexible-array member (FAM) and a set of members that would otherwise follow it (in this case `u8 rss_hash_key_data[VIRTIO_NET_RSS_MAX_KEY_SIZE];`). This overlays the trailing members (rss_hash_key_data) onto the FAM (hash_key_data) while keeping the FAM and the start of MEMBERS aligned. The static_assert() ensures this alignment remains. Notice that due to tail padding in flexible `struct virtio_net_rss_config_trailer`, `rss_trailer.hash_key_data` (at offset 83 in struct virtnet_info) and `rss_hash_key_data` (at offset 84 in struct virtnet_info) are misaligned by one byte. See below: struct virtio_net_rss_config_trailer { __le16 max_tx_vq; /* 0 2 */ __u8 hash_key_length; /* 2 1 */ __u8 hash_key_data[]; /* 3 0 */ /* size: 4, cachelines: 1, members: 3 */ /* padding: 1 */ /* last cacheline: 4 bytes */ }; struct virtnet_info { ... struct virtio_net_rss_config_trailer rss_trailer; /* 80 4 */ /* XXX last struct has 1 byte of padding */ u8 rss_hash_key_data[40]; /* 84 40 */ ... /* size: 832, cachelines: 13, members: 48 */ /* sum members: 801, holes: 8, sum holes: 31 */ /* paddings: 2, sum paddings: 5 */ }; After changes, those members are correctly aligned at offset 795: struct virtnet_info { ... union { struct virtio_net_rss_config_trailer rss_trailer; /* 792 4 */ struct { unsigned char __offset_to_hash_key_data[3]; /* 792 3 */ u8 rss_hash_key_data[40]; /* 795 40 */ }; /* 792 43 */ }; /* 792 44 */ ... /* size: 840, cachelines: 14, members: 47 */ /* sum members: 801, holes: 8, sum holes: 35 */ /* padding: 4 */ /* paddings: 1, sum paddings: 4 */ /* last cacheline: 8 bytes */ }; As a result, the RSS key passed to the device is shifted by 1 byte: the last byte is cut off, and instead a (possibly uninitialized) byte is added at the beginning. As a last note `struct virtio_net_rss_config_hdr *rss_hdr;` is also moved to the end, since it seems those three members should stick around together. :) Cc: stable@vger.kernel.org Fixes: ed3100e90d0d ("virtio_net: Use new RSS config structs") Signed-off-by: Gustavo A. R. Silva Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/aWIItWq5dV9XTTCJ@kspp Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

virtio_net: fix device mismatch in devm_kzalloc/devm_kfree

2026-01-17T15:35:24+00:00

[ Upstream commit acb4bc6e1ba34ae1a34a9334a1ce8474c909466e ] Initial rss_hdr allocation uses virtio_device->device, but virtnet_set_queues() frees using net_device->device. This device mismatch causing below devres warning [ 3788.514041] ------------[ cut here ]------------ [ 3788.514044] WARNING: drivers/base/devres.c:1095 at devm_kfree+0x84/0x98, CPU#16: vdpa/1463 [ 3788.514054] Modules linked in: octep_vdpa virtio_net virtio_vdpa [last unloaded: virtio_vdpa] [ 3788.514064] CPU: 16 UID: 0 PID: 1463 Comm: vdpa Tainted: G W 6.18.0 #10 PREEMPT [ 3788.514067] Tainted: [W]=WARN [ 3788.514069] Hardware name: Marvell CN106XX board (DT) [ 3788.514071] pstate: 63400009 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) [ 3788.514074] pc : devm_kfree+0x84/0x98 [ 3788.514076] lr : devm_kfree+0x54/0x98 [ 3788.514079] sp : ffff800084e2f220 [ 3788.514080] x29: ffff800084e2f220 x28: ffff0003b2366000 x27: 000000000000003f [ 3788.514085] x26: 000000000000003f x25: ffff000106f17c10 x24: 0000000000000080 [ 3788.514089] x23: ffff00045bb8ab08 x22: ffff00045bb8a000 x21: 0000000000000018 [ 3788.514093] x20: ffff0004355c3080 x19: ffff00045bb8aa00 x18: 0000000000080000 [ 3788.514098] x17: 0000000000000040 x16: 000000000000001f x15: 000000000007ffff [ 3788.514102] x14: 0000000000000488 x13: 0000000000000005 x12: 00000000000fffff [ 3788.514106] x11: ffffffffffffffff x10: 0000000000000005 x9 : ffff800080c8c05c [ 3788.514110] x8 : ffff800084e2eeb8 x7 : 0000000000000000 x6 : 000000000000003f [ 3788.514115] x5 : ffff8000831bafe0 x4 : ffff800080c8b010 x3 : ffff0004355c3080 [ 3788.514119] x2 : ffff0004355c3080 x1 : 0000000000000000 x0 : 0000000000000000 [ 3788.514123] Call trace: [ 3788.514125] devm_kfree+0x84/0x98 (P) [ 3788.514129] virtnet_set_queues+0x134/0x2e8 [virtio_net] [ 3788.514135] virtnet_probe+0x9c0/0xe00 [virtio_net] [ 3788.514139] virtio_dev_probe+0x1e0/0x338 [ 3788.514144] really_probe+0xc8/0x3a0 [ 3788.514149] __driver_probe_device+0x84/0x170 [ 3788.514152] driver_probe_device+0x44/0x120 [ 3788.514155] __device_attach_driver+0xc4/0x168 [ 3788.514158] bus_for_each_drv+0x8c/0xf0 [ 3788.514161] __device_attach+0xa4/0x1c0 [ 3788.514164] device_initial_probe+0x1c/0x30 [ 3788.514168] bus_probe_device+0xb4/0xc0 [ 3788.514170] device_add+0x614/0x828 [ 3788.514173] register_virtio_device+0x214/0x258 [ 3788.514175] virtio_vdpa_probe+0xa0/0x110 [virtio_vdpa] [ 3788.514179] vdpa_dev_probe+0xa8/0xd8 [ 3788.514183] really_probe+0xc8/0x3a0 [ 3788.514186] __driver_probe_device+0x84/0x170 [ 3788.514189] driver_probe_device+0x44/0x120 [ 3788.514192] __device_attach_driver+0xc4/0x168 [ 3788.514195] bus_for_each_drv+0x8c/0xf0 [ 3788.514197] __device_attach+0xa4/0x1c0 [ 3788.514200] device_initial_probe+0x1c/0x30 [ 3788.514203] bus_probe_device+0xb4/0xc0 [ 3788.514206] device_add+0x614/0x828 [ 3788.514209] _vdpa_register_device+0x58/0x88 [ 3788.514211] octep_vdpa_dev_add+0x104/0x228 [octep_vdpa] [ 3788.514215] vdpa_nl_cmd_dev_add_set_doit+0x2d0/0x3c0 [ 3788.514218] genl_family_rcv_msg_doit+0xe4/0x158 [ 3788.514222] genl_rcv_msg+0x218/0x298 [ 3788.514225] netlink_rcv_skb+0x64/0x138 [ 3788.514229] genl_rcv+0x40/0x60 [ 3788.514233] netlink_unicast+0x32c/0x3b0 [ 3788.514237] netlink_sendmsg+0x170/0x3b8 [ 3788.514241] __sys_sendto+0x12c/0x1c0 [ 3788.514246] __arm64_sys_sendto+0x30/0x48 [ 3788.514249] invoke_syscall.constprop.0+0x58/0xf8 [ 3788.514255] do_el0_svc+0x48/0xd0 [ 3788.514259] el0_svc+0x48/0x210 [ 3788.514264] el0t_64_sync_handler+0xa0/0xe8 [ 3788.514268] el0t_64_sync+0x198/0x1a0 [ 3788.514271] ---[ end trace 0000000000000000 ]--- Fix by using virtio_device->device consistently for allocation and deallocation Fixes: 4944be2f5ad8c ("virtio_net: Allocate rss_hdr with devres") Signed-off-by: Kommula Shiva Shankar Acked-by: Michael S. Tsirkin Acked-by: Jason Wang Reviewed-by: Xuan Zhuo Link: https://patch.msgid.link/20260102101900.692770-1-kshankar@marvell.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

virtio-net: avoid unnecessary checksum calculation on guest RX

2025-11-27T03:45:54+00:00

Commit a2fb4bc4e2a6 ("net: implement virtio helpers to handle UDP GSO tunneling.") inadvertently altered checksum offload behavior for guests not using UDP GSO tunneling. Before, tun_put_user called tun_vnet_hdr_from_skb, which passed has_data_valid = true to virtio_net_hdr_from_skb. After, tun_put_user began calling tun_vnet_hdr_tnl_from_skb instead, which passes has_data_valid = false into both call sites. This caused virtio hdr flags to not include VIRTIO_NET_HDR_F_DATA_VALID for SKBs where skb->ip_summed == CHECKSUM_UNNECESSARY. As a result, guests are forced to recalculate checksums unnecessarily. Restore the previous behavior by ensuring has_data_valid = true is passed in the !tnl_gso_type case, but only from tun side, as virtio_net_hdr_tnl_from_skb() is used also by the virtio_net driver, which in turn must not use VIRTIO_NET_HDR_F_DATA_VALID on tx. cc: stable@vger.kernel.org Fixes: a2fb4bc4e2a6 ("net: implement virtio helpers to handle UDP GSO tunneling.") Signed-off-by: Jon Kohler Acked-by: Michael S. Tsirkin Acked-by: Jason Wang Link: https://patch.msgid.link/20251125222754.1737443-1-jon@nutanix.com Signed-off-by: Jakub Kicinski

virtio-net: fix incorrect flags recording in big mode

2025-11-13T12:16:30+00:00

The purpose of commit 703eec1b2422 ("virtio_net: fixing XDP for fully checksummed packets handling") is to record the flags in advance, as their value may be overwritten in the XDP case. However, the flags recorded under big mode are incorrect, because in big mode, the passed buf does not point to the rx buffer, but rather to the page of the submitted buffer. This commit fixes this issue. For the small mode, the commit c11a49d58ad2 ("virtio_net: Fix mismatched buf address when unmapping for small packets") fixed it. Tested-by: Alyssa Ross Fixes: 703eec1b2422 ("virtio_net: fixing XDP for fully checksummed packets handling") Signed-off-by: Xuan Zhuo Acked-by: Jason Wang Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/20251111090828.23186-1-xuanzhuo@linux.alibaba.com Signed-off-by: Paolo Abeni

virtio-net: fix received length check in big packets

2025-11-05T02:49:29+00:00

Since commit 4959aebba8c0 ("virtio-net: use mtu size as buffer length for big packets"), when guest gso is off, the allocated size for big packets is not MAX_SKB_FRAGS * PAGE_SIZE anymore but depends on negotiated MTU. The number of allocated frags for big packets is stored in vi->big_packets_num_skbfrags. Because the host announced buffer length can be malicious (e.g. the host vhost_net driver's get_rx_bufs is modified to announce incorrect length), we need a check in virtio_net receive path. Currently, the check is not adapted to the new change which can lead to NULL page pointer dereference in the below while loop when receiving length that is larger than the allocated one. This commit fixes the received length check corresponding to the new change. Fixes: 4959aebba8c0 ("virtio-net: use mtu size as buffer length for big packets") Cc: stable@vger.kernel.org Signed-off-by: Bui Quang Minh Reviewed-by: Xuan Zhuo Tested-by: Lei Yang Link: https://patch.msgid.link/20251030144438.7582-1-minhquangbui99@gmail.com Signed-off-by: Jakub Kicinski

virtio_net: fix alignment for virtio_net_hdr_v1_hash

2025-11-05T01:14:07+00:00

Changing alignment of header would mean it's no longer safe to cast a 2 byte aligned pointer between formats. Use two 16 bit fields to make it 2 byte aligned as previously. This fixes the performance regression since commit ("virtio_net: enable gso over UDP tunnel support.") as it uses virtio_net_hdr_v1_hash_tunnel which embeds virtio_net_hdr_v1_hash. Pktgen in guest + XDP_DROP on TAP + vhost_net shows the TX PPS is recovered from 2.4Mpps to 4.45Mpps. Fixes: 56a06bd40fab ("virtio_net: enable gso over UDP tunnel support.") Cc: stable@vger.kernel.org Signed-off-by: Michael S. Tsirkin Signed-off-by: Jason Wang Tested-by: Lei Yang Link: https://patch.msgid.link/20251031060551.126-1-jasowang@redhat.com Signed-off-by: Jakub Kicinski