kernel/linux.git/net/core, branch v6.12.107

net: gro: properly validate BIG TCP aggregation criteria

2026-08-27T12:32:08+00:00

When GRO attempts to aggregate packets beyond GRO_LEGACY_MAX_SIZE (64KB), BIG TCP should only be permitted for plain IPv4 TCP and plain IPv6 TCP (with sufficient MAC header room to insert the temporary HBH jumbo header). However, commit b1a78b9b9886 ("net: add support for ipv4 big tcp") loosened the check in skb_gro_receive(), leading to several issues: 1. skb_gro_receive() checked skb_headroom(p) instead of the actual space before the MAC header (p->mac_header). Because skb_headroom(p) includes mac_len, crafted frames (e.g. injected via AF_PACKET) can pass the check with p->mac_header < 8 bytes. When ipv6_gro_complete() inserts the temporary HBH jumbo header, the memmove() starts before skb->head, causing an out-of-bounds write and wrapping skb->mac_header. 2. It allowed non-IP protocols such as software VLAN (ETH_P_8021Q / ETH_P_8021AD) to aggregate beyond 64KB because p->protocol != ETH_P_IPV6 was true. 3. It checked p->encapsulation instead of NAPI_GRO_CB(skb)->encap_mark, allowing encapsulated flows (e.g. SIT / IPv6-in-IPv4) to aggregate beyond 64KB. Fix skb_gro_receive() to strictly enforce: - NAPI_GRO_CB(skb)->proto == IPPROTO_TCP - Not encapsulated (!NAPI_GRO_CB(skb)->encap_mark && !p->encapsulation) - Protocol must be either ETH_P_IP or ETH_P_IPV6 - If ETH_P_IPV6, p->mac_header must be at least sizeof(struct hop_jumbo_hdr) Returning -E2BIG from skb_gro_receive() ensures that packets which cannot become BIG TCP are cleanly flushed at <= 64KB and delivered intact without dropping. This issue does not exist in mainline (7.0+) because the subsystem was rewritten in commit 81be30c1f5f2 ("net/ipv6: Drop HBH for BIG TCP on RX side"), making this fix relevant only for older stable branches like 6.18.y. Fixes: 0fe79f28bfaf ("net: allow gro_max_size to exceed 65536") Fixes: b1a78b9b9886 ("net: add support for ipv4 big tcp") Reported-by: Sam Dlinn Cc: stable@vger.kernel.org Signed-off-by: Eric Dumazet Signed-off-by: Greg Kroah-Hartman

net: harmonize tstats and dstats

2026-08-23T12:22:51+00:00

commit d3ed6dee73c560fad0a8e152c8e233b3fb3a2e44 upstream. After the blamed commits below, some UDP tunnel use dstats for accounting. On the xmit path, all the UDP-base tunnels ends up using iptunnel_xmit_stats() for stats accounting, and the latter assumes the relevant (tunnel) network device uses tstats. The end result is some 'funny' stat report for the mentioned UDP tunnel, e.g. when no packet is actually dropped and a bunch of packets are transmitted: gnv2: mtu 1450 qdisc noqueue \ state UNKNOWN mode DEFAULT group default qlen 1000 link/ether ee:7d:09:87:90:ea brd ff:ff:ff:ff:ff:ff RX: bytes packets errors dropped missed mcast 14916 23 0 15 0 0 TX: bytes packets errors dropped carrier collsns 0 1566 0 0 0 0 Address the issue ensuring the same binary layout for the overlapping fields of dstats and tstats. While this solution is a bit hackish, is smaller and with no performance pitfall compared to other alternatives i.e. supporting both dstat and tstat in iptunnel_xmit_stats() or reverting the blamed commit. With time we should possibly move all the IP-based tunnel (and virtual devices) to dstats. Fixes: c77200c07491 ("bareudp: Handle stats using NETDEV_PCPU_STAT_DSTATS.") Fixes: 6fa6de302246 ("geneve: Handle stats using NETDEV_PCPU_STAT_DSTATS.") Fixes: be226352e8dc ("vxlan: Handle stats using NETDEV_PCPU_STAT_DSTATS.") Signed-off-by: Paolo Abeni Reviewed-by: Guillaume Nault Link: https://patch.msgid.link/2e1c444cf0f63ae472baff29862c4c869be17031.1738432804.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: pktgen: fix proc entry use-after-free

2026-08-23T12:22:46+00:00

[ Upstream commit 817ff6efdb7f484ea547218e11e17d8e43daa3b4 ] pktgen_change_name() replaces pkt_dev->entry while holding t->if_lock. pktgen_remove_device() removes the same entry before _rem_dev_from_if_list() takes that lock. This allows the following interleaving: CPU 0 (NETDEV_CHANGENAME) CPU 1 (kpktgend) if_lock(t) proc_remove(pkt_dev->entry) proc_remove(pkt_dev->entry) pkt_dev->entry = proc_create_data(...) if_unlock(t) The kthread can pass the stale proc_dir_entry to proc_remove() after the rename path has freed it. A reproducer with a widened race window reports: BUG: KASAN: slab-use-after-free in proc_remove+0x78/0x80 Read of size 8 at addr ffff8881478fea70 by task kpktgend_0/67 Call Trace: proc_remove+0x78/0x80 pktgen_remove_device.isra.0+0x11c/0x4c0 pktgen_thread_worker+0x1214/0x6bc0 kthread+0x2c6/0x3b0 Allocated by task 95: __proc_create+0x204/0x790 proc_create_data+0x72/0xe0 pktgen_thread_write+0xd61/0x1510 Freed by task 28: kmem_cache_free+0xcb/0x3d0 proc_free_inode+0x5b/0x80 rcu_core+0x50a/0x1850 The buggy address belongs to the object at ffff8881478fea00 which belongs to the cache proc_dir_entry of size 192 Move proc_remove() into the if_lock-protected list removal helper. Keep it before list_del_rcu() to preserve the ordering required by add_device(). The rename path must then finish replacing the entry before removal, or it observes that the device is no longer on the list. Fixes: 39df232f1a9b ("[PKTGEN]: fix device name handling") Cc: stable@vger.kernel.org Signed-off-by: Chengfeng Ye Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260719145740.2888967-1-nicoyip.dev@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net: pktgen: fix code style (WARNING: Block comments)

2026-08-23T12:22:46+00:00

[ Upstream commit 870b856cb478bc02fffe4d89897e62c692efb09a ] Fix checkpatch code style warnings: WARNING: Block comments use a trailing */ on a separate line + * removal by worker thread */ WARNING: Block comments use * on subsequent lines + __u8 tos; /* six MSB of (former) IPv4 TOS + are for dscp codepoint */ WARNING: Block comments use a trailing */ on a separate line + are for dscp codepoint */ WARNING: Block comments use * on subsequent lines + __u8 traffic_class; /* ditto for the (former) Traffic Class in IPv6 + (see RFC 3260, sec. 4) */ WARNING: Block comments use a trailing */ on a separate line + (see RFC 3260, sec. 4) */ WARNING: Block comments use * on subsequent lines + /* = { + 0x00, 0x80, 0xC8, 0x79, 0xB3, 0xCB, WARNING: Block comments use * on subsequent lines + /* Field for thread to receive "posted" events terminate, + stop ifs etc. */ WARNING: Block comments use a trailing */ on a separate line + stop ifs etc. */ WARNING: Block comments should align the * on each line + * we go look for it ... +*/ WARNING: Block comments use a trailing */ on a separate line + * we resolve the dst issue */ WARNING: Block comments use a trailing */ on a separate line + * with proc_create_data() */ Signed-off-by: Peter Seiderer Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Jakub Kicinski Stable-dep-of: 817ff6efdb7f ("net: pktgen: fix proc entry use-after-free") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

xdp: reject clones that overrun skb_shared_info tailroom

2026-08-19T16:14:28+00:00

commit e48e8edbef2eb824201495daa5234560f632b23c upstream. xdpf_clone() clones broadcast copies into a single page and sets frame_sz to PAGE_SIZE. __xdp_build_skb_from_frame() later treats that page like a normal XDP frame and expects the usual skb_shared_info tailroom at the end of the buffer. The current check only rejects frames whose linear xdp_frame header, headroom, and packet data exceed PAGE_SIZE. A source frame backed by a larger allocation can still satisfy that check while extending into the clone's required shared-info area. When such a clone is converted back into an skb, build_skb_around() places skb_shared_info over live packet bytes and later writes can corrupt XDP return metadata. Reject clones unless their linear area fits inside SKB_WITH_OVERHEAD(PAGE_SIZE), matching the tailroom requirement already enforced by the XDP-to-skb conversion path. Fixes: e624d4ed4aa8 ("xdp: Extend xdp_redirect_map with broadcast support") Cc: stable@vger.kernel.org Reported-by: Vega Signed-off-by: Zhiling Zou Link: https://patch.msgid.link/6b2afef5d1738763c6965e8e466eb16e43e4f956.1785757386.git.zhilinz@nebusec.ai Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: fix skb length accounting after generic XDP frag adjustment

2026-08-19T16:14:18+00:00

commit 33f2b2eb33d666ecac68031e0f31424fb70528db upstream. Generic XDP exposes non-linear skb fragments through an xdp_buff. If an XDP program adjusts the fragment area, bpf_prog_run_generic_xdp() copies xdp_frags_size back to skb->data_len but leaves skb->len containing the old fragment contribution. After a fragment shrink, this makes skb_headlen() larger than the actual linear area. In the reproduced UDP receive path, __skb_datagram_iter() copied 1024 bytes past the actual linear tail to userspace, starting at struct skb_shared_info. The copied bytes included the affected skb's nr_frags, xdp_frags_size and a kernel pointer from skb_shinfo(skb)->frags[0]. Real packet data was displaced by the same amount and truncated at the end. Subtract the old data_len before replacing it and add the new data_len afterwards, keeping skb->len and skb->data_len synchronized. A 60000-byte UDP datagram on a veth pair with MTU 64000 was shortened by 1024 bytes from its fragment area. Before the fix, all 10 runs produced corrupted payloads. After the fix, all 10 runs matched the expected payload exactly. Fixes: e6d5dbdd20aa ("xdp: add multi-buff support for xdp running in generic mode") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/bpf/al9T9Eto%2FhRIzP5W@boxer/ Reviewed-by: Mohsin Bashir Acked-by: Lorenzo Bianconi Signed-off-by: Sun Jian Link: https://patch.msgid.link/20260804054040.613675-2-sun.jian.kdev@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: remove WARN_ON_ONCE() from sk_mc_loop()

2026-08-19T16:14:12+00:00

[ Upstream commit b8a39a09ae4eaae04309e1e38ed6a1101d967496 ] sk_mc_loop() can be called for sockets that are neither AF_INET nor AF_INET6 (e.g. AF_PACKET sockets when sending packets via raw/packet socket over virtual devices such as VRF or ipvlan). In such cases, sk_family is not AF_INET/AF_INET6 and sk_mc_loop() falls through the switch statement and triggers WARN_ON_ONCE(1). Non-INET sockets do not support IP_MULTICAST_LOOP or IPV6_MULTICAST_LOOP options, so loopback should default to true without generating a warning. Fixes: f60e5990d9c1 ("ipv6: protect skb->sk accesses from recursive dereference inside the stack") Reported-by: syzbot+22c3218a6fa219e47321@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6a72024c.13623e66.bdc14.0019.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260804152048.2134341-1-edumazet@google.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

veth: convert frag_list skbs before running XDP

2026-08-09T18:23:15+00:00

commit d0d6415963040c401e7a7e4e482a698ba52448cb upstream. A frag_list skb can reach veth with data_len set but nr_frags zero. veth_convert_skb_to_xdp_buff() only converts skbs that are shared, locked, have frags[], or do not have enough headroom. It later uses skb_is_nonlinear() to decide whether to set XDP_FLAGS_HAS_FRAGS and xdp_frags_size. That exposes frag_list data to XDP as if it were stored in frags[], but frags[] is empty. AF_XDP copy mode can then trust the bogus XDP fragment metadata, walk an empty fragment entry, and crash in memcpy() from __xsk_rcv(). Route non-linear skbs through skb_pp_cow_data() before exposing them to XDP, and only advertise XDP frags when the resulting skb has frags[]. skb_copy_bits() already handles frag_list input, and skb_pp_cow_data() builds frags[] output with skb_add_rx_frag(), which is the representation XDP multi-buffer expects. Fixes: 718a18a0c8a6 ("veth: Rework veth_xdp_rcv_skb in order to accept non-linear skb") Cc: stable@vger.kernel.org Signed-off-by: Matt Fleming Reviewed-by: Toke Høiland-Jørgensen Acked-by: Lorenzo Bianconi Link: https://patch.msgid.link/20260722191925.2192070-1-matt@readmodwrite.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

bpf: lwt: Fix dst reference leak on reroute failure

2026-08-09T18:23:12+00:00

commit 88c17de85ddb459c3fe1e3c65d61fa366b1cf0a8 upstream. bpf_lwt_xmit_reroute() obtains a referenced dst from the route lookup. When skb_cow_head() fails before that dst is installed on the skb, the error path only frees the skb. The skb still owns its previous dst, so the newly looked up dst reference is leaked. Release the new dst reference before freeing the skb on this error path. Fixes: 3bd0b15281af ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c") Cc: stable@vger.kernel.org Signed-off-by: Xuanqiang Luo Link: https://patch.msgid.link/20260723060445.21926-1-xuanqiang.luo@linux.dev Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

bpf: Fix same-register dst/src OOB read and pointer leak in sock_ops

2026-08-03T09:17:29+00:00

[ Upstream commit 10f86a2a5c91fc4c4d001960f1c21abe52545ef6 ] When a BPF sock_ops program accesses ctx fields with dst_reg == src_reg, the SOCK_OPS_GET_SK() and SOCK_OPS_GET_FIELD() macros fail to zero the destination register in the !fullsock / !locked_tcp_sock path. Both macros borrow a temporary register to check is_fullsock / is_locked_tcp_sock when dst_reg == src_reg, because dst_reg holds the ctx pointer. When the check is false (e.g., TCP_NEW_SYN_RECV state with a request_sock), dst_reg should be zeroed but is not, leaving the stale ctx pointer: - SOCK_OPS_GET_SK: dst_reg retains the ctx pointer, passes NULL checks as PTR_TO_SOCKET_OR_NULL, and can be used as a bogus socket pointer, leading to stack-out-of-bounds access in helpers like bpf_skc_to_tcp6_sock(). - SOCK_OPS_GET_FIELD: dst_reg retains the ctx pointer which the verifier believes is a SCALAR_VALUE, leaking a kernel pointer. Fix both macros by: - Changing JMP_A(1) to JMP_A(2) in the fullsock path to skip the added instruction. - Adding BPF_MOV64_IMM(si->dst_reg, 0) after the temp register restore in the !fullsock path, placed after the restore because dst_reg == src_reg means we need src_reg intact to read ctx->temp. Fixes: fd09af010788 ("bpf: sock_ops ctx access may stomp registers in corner case") Fixes: 84f44df664e9 ("bpf: sock_ops sk access may stomp registers when dst_reg = src_reg") Reported-by: Quan Sun <2022090917019@std.uestc.edu.cn> Reported-by: Yinhao Hu Reported-by: Kaiyan Mei Reported-by: Dongliang Mu Reviewed-by: Emil Tsalapatis Closes: https://lore.kernel.org/bpf/6fe1243e-149b-4d3b-99c7-fcc9e2f75787@std.uestc.edu.cn/T/#u Signed-off-by: Jiayuan Chen Acked-by: Martin KaFai Lau Link: https://patch.msgid.link/20260407022720.162151-2-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin Signed-off-by: Jay Wang Signed-off-by: Sasha Levin