kernel/linux.git/include/linux/skbuff.h, branch v6.6.131

net: Add skb_dstref_steal and skb_dstref_restore

2026-03-04T12:19:53+00:00

[ Upstream commit c3f0c02997c7f8489fec259e28e0e04e9811edac ] Going forward skb_dst_set will assert that skb dst_entry is empty during skb_dst_set to prevent potential leaks. There are few places that still manually manage dst_entry not using the helpers. Convert them to the following new helpers: - skb_dstref_steal that resets dst_entry and returns previous dst_entry value - skb_dstref_restore that restores dst_entry previously reset via skb_dstref_steal Signed-off-by: Stanislav Fomichev Link: https://patch.msgid.link/20250818154032.3173645-2-sdf@fomichev.me Signed-off-by: Jakub Kicinski Stable-dep-of: 81b84de32bb2 ("xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path") Signed-off-by: Sasha Levin

net: add skb_header_pointer_careful() helper

2026-02-11T12:39:14+00:00

[ Upstream commit 13e00fdc9236bd4d0bff4109d2983171fbcb74c4 ] This variant of skb_header_pointer() should be used in contexts where @offset argument is user-controlled and could be negative. Negative offsets are supported, as long as the zone starts between skb->head and skb->data. Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260128141539.3404400-2-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: cabd1a976375 ("net/sched: cls_u32: use skb_header_pointer_careful()") Signed-off-by: Sasha Levin

netmem: fix skb_frag_address_safe with unreadable skbs

2025-08-28T14:28:23+00:00

[ Upstream commit 4672aec56d2e8edabcb74c3e2320301d106a377e ] skb_frag_address_safe() needs a check that the skb_frag_page exists check similar to skb_frag_address(). Cc: ap420073@gmail.com Signed-off-by: Mina Almasry Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250619175239.3039329-1-almasrymina@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: reject malicious packets in ipv6_gso_segment()

2025-08-15T10:09:02+00:00

[ Upstream commit d45cf1e7d7180256e17c9ce88e32e8061a7887fe ] syzbot was able to craft a packet with very long IPv6 extension headers leading to an overflow of skb->transport_header. This 16bit field has a limited range. Add skb_reset_transport_header_careful() helper and use it from ipv6_gso_segment() WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 skb_reset_transport_header include/linux/skbuff.h:3032 [inline] WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151 Modules linked in: CPU: 0 UID: 0 PID: 5871 Comm: syz-executor211 Not tainted 6.16.0-rc6-syzkaller-g7abc678e3084 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:skb_reset_transport_header include/linux/skbuff.h:3032 [inline] RIP: 0010:ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151 Call Trace: skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53 nsh_gso_segment+0x54a/0xe10 net/nsh/nsh.c:110 skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53 __skb_gso_segment+0x342/0x510 net/core/gso.c:124 skb_gso_segment include/net/gso.h:83 [inline] validate_xmit_skb+0x857/0x11b0 net/core/dev.c:3950 validate_xmit_skb_list+0x84/0x120 net/core/dev.c:4000 sch_direct_xmit+0xd3/0x4b0 net/sched/sch_generic.c:329 __dev_xmit_skb net/core/dev.c:4102 [inline] __dev_queue_xmit+0x17b6/0x3a70 net/core/dev.c:4679 Fixes: d1da932ed4ec ("ipv6: Separate ipv6 offload support") Reported-by: syzbot+af43e647fd835acc02df@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/688a1a05.050a0220.5d226.0008.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Reviewed-by: Dawid Osuchowski Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250730131738.3385939-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: Rename mono_delivery_time to tstamp_type for scalabilty

2025-05-09T07:43:57+00:00

[ Upstream commit 4d25ca2d6801cfcf26f7f39c561611ba5be99bf8 ] mono_delivery_time was added to check if skb->tstamp has delivery time in mono clock base (i.e. EDT) otherwise skb->tstamp has timestamp in ingress and delivery_time at egress. Renaming the bitfield from mono_delivery_time to tstamp_type is for extensibilty for other timestamps such as userspace timestamp (i.e. SO_TXTIME) set via sock opts. As we are renaming the mono_delivery_time to tstamp_type, it makes sense to start assigning tstamp_type based on enum defined in this commit. Earlier we used bool arg flag to check if the tstamp is mono in function skb_set_delivery_time, Now the signature of the functions accepts tstamp_type to distinguish between mono and real time. Also skb_set_delivery_type_by_clockid is a new function which accepts clockid to determine the tstamp_type. In future tstamp_type:1 can be extended to support userspace timestamp by increasing the bitfield. Signed-off-by: Abhishek Chauhan Reviewed-by: Willem de Bruijn Reviewed-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20240509211834.3235191-2-quic_abchauha@quicinc.com Signed-off-by: Martin KaFai Lau Stable-dep-of: 3908feb1bd7f ("Bluetooth: L2CAP: copy RX timestamp to new fragments") Signed-off-by: Sasha Levin

xfrm: Preserve vlan tags for transport mode software GRO

2024-05-17T10:02:20+00:00

[ Upstream commit 58fbfecab965014b6e3cc956a76b4a96265a1add ] The software GRO path for esp transport mode uses skb_mac_header_rebuild prior to re-injecting the packet via the xfrm_napi_dev. This only copies skb->mac_len bytes of header which may not be sufficient if the packet contains 802.1Q tags or other VLAN tags. Worse copying only the initial header will leave a packet marked as being VLAN tagged but without the corresponding tag leading to mangling when it is later untagged. The VLAN tags are important when receiving the decrypted esp transport mode packet after GRO processing to ensure it is received on the correct interface. Therefore record the full mac header length in xfrm*_transport_input for later use in corresponding xfrm*_transport_finish to copy the entire mac header when rebuilding the mac header for GRO. The skb->data pointer is left pointing skb->mac_header bytes after the start of the mac header as is expected by the network stack and network and transport header offsets reset to this location. Fixes: 7785bba299a8 ("esp: Add a software GRO codepath") Signed-off-by: Paul Davey Signed-off-by: Steffen Klassert Signed-off-by: Sasha Levin

net: mpls: error out if inner headers are not set

2024-04-13T11:07:41+00:00

commit 025f8ad20f2e3264d11683aa9cbbf0083eefbdcd upstream. mpls_gso_segment() assumes skb_inner_network_header() returns a valid result: mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb); if (unlikely(!mpls_hlen || mpls_hlen % MPLS_HLEN)) goto out; if (unlikely(!pskb_may_pull(skb, mpls_hlen))) With syzbot reproducer, skb_inner_network_header() yields 0, skb_network_header() returns 108, so this will "pskb_may_pull(skb, -108)))" which triggers a newly added DEBUG_NET_WARN_ON_ONCE() check: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 5068 at include/linux/skbuff.h:2723 pskb_may_pull_reason include/linux/skbuff.h:2723 [inline] WARNING: CPU: 0 PID: 5068 at include/linux/skbuff.h:2723 pskb_may_pull include/linux/skbuff.h:2739 [inline] WARNING: CPU: 0 PID: 5068 at include/linux/skbuff.h:2723 mpls_gso_segment+0x773/0xaa0 net/mpls/mpls_gso.c:34 [..] skb_mac_gso_segment+0x383/0x740 net/core/gso.c:53 nsh_gso_segment+0x40a/0xad0 net/nsh/nsh.c:108 skb_mac_gso_segment+0x383/0x740 net/core/gso.c:53 __skb_gso_segment+0x324/0x4c0 net/core/gso.c:124 skb_gso_segment include/net/gso.h:83 [inline] [..] sch_direct_xmit+0x11a/0x5f0 net/sched/sch_generic.c:327 [..] packet_sendmsg+0x46a9/0x6130 net/packet/af_packet.c:3113 [..] First iteration of this patch made mpls_hlen signed and changed test to error out to "mpls_hlen <= 0 || ..". Eric Dumazet said: > I was thinking about adding a debug check in skb_inner_network_header() > if inner_network_header is zero (that would mean it is not 'set' yet), > but this would trigger even after your patch. So add new skb_inner_network_header_was_set() helper and use that. The syzbot reproducer injects data via packet socket. The skb that gets allocated and passed down the stack has ->protocol set to NSH (0x894f) and gso_type set to SKB_GSO_UDP | SKB_GSO_DODGY. This gets passed to skb_mac_gso_segment(), which sees NSH as ptype to find a callback for. nsh_gso_segment() retrieves next type: proto = tun_p_to_eth_p(nsh_hdr(skb)->np); ... which is MPLS (TUN_P_MPLS_UC). It updates skb->protocol and then calls mpls_gso_segment(). Inner offsets are all 0, so mpls_gso_segment() ends up with a negative header size. In case more callers rely on silent handling of such large may_pull values we could also 'legalize' this behaviour, either replacing the debug check with (len > INT_MAX) test or removing it and instead adding a comment before existing if (unlikely(len > skb->len)) return SKB_DROP_REASON_PKT_TOO_SMALL; test in pskb_may_pull_reason(), saying that this check also implicitly takes care of callers that miscompute header sizes. Cc: Simon Horman Fixes: 219eee9c0d16 ("net: skbuff: add overflow debug check to pull/push helpers") Reported-by: syzbot+99d15fcdb0132a1e1a82@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/00000000000043b1310611e388aa@google.com/raw Signed-off-by: Florian Westphal Link: https://lore.kernel.org/r/20240222140321.14080-1-fw@strlen.de Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: skbuff: add overflow debug check to pull/push helpers

2024-04-13T11:07:30+00:00

[ Upstream commit 219eee9c0d16f1b754a8b85275854ab17df0850a ] syzbot managed to trigger following splat: BUG: KASAN: use-after-free in __skb_flow_dissect+0x4a3b/0x5e50 Read of size 1 at addr ffff888208a4000e by task a.out/2313 [..] __skb_flow_dissect+0x4a3b/0x5e50 __skb_get_hash+0xb4/0x400 ip_tunnel_xmit+0x77e/0x26f0 ipip_tunnel_xmit+0x298/0x410 .. Analysis shows that the skb has a valid ->head, but bogus ->data pointer. skb->data gets its bogus value via the neigh layer, which does: 1556 __skb_pull(skb, skb_network_offset(skb)); ... and the skb was already dodgy at this point: skb_network_offset(skb) returns a negative value due to an earlier overflow of skb->network_header (u16). __skb_pull thus "adjusts" skb->data by a huge offset, pointing outside skb->head area. Allow debug builds to splat when we try to pull/push more than INT_MAX bytes. After this, the syzkaller reproducer yields a more precise splat before the flow dissector attempts to read off skb->data memory: WARNING: CPU: 5 PID: 2313 at include/linux/skbuff.h:2653 neigh_connected_output+0x28e/0x400 ip_finish_output2+0xb25/0xed0 iptunnel_xmit+0x4ff/0x870 ipgre_xmit+0x78e/0xbb0 Signed-off-by: Florian Westphal Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20240216113700.23013-1-fw@strlen.de Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

inet: inet_defrag: prevent sk release while still in use

2024-04-10T14:35:44+00:00

[ Upstream commit 18685451fc4e546fc0e718580d32df3c0e5c8272 ] ip_local_out() and other functions can pass skb->sk as function argument. If the skb is a fragment and reassembly happens before such function call returns, the sk must not be released. This affects skb fragments reassembled via netfilter or similar modules, e.g. openvswitch or ct_act.c, when run as part of tx pipeline. Eric Dumazet made an initial analysis of this bug. Quoting Eric: Calling ip_defrag() in output path is also implying skb_orphan(), which is buggy because output path relies on sk not disappearing. A relevant old patch about the issue was : 8282f27449bf ("inet: frag: Always orphan skbs inside ip_defrag()") [..] net/ipv4/ip_output.c depends on skb->sk being set, and probably to an inet socket, not an arbitrary one. If we orphan the packet in ipvlan, then downstream things like FQ packet scheduler will not work properly. We need to change ip_defrag() to only use skb_orphan() when really needed, ie whenever frag_list is going to be used. Eric suggested to stash sk in fragment queue and made an initial patch. However there is a problem with this: If skb is refragmented again right after, ip_do_fragment() will copy head->sk to the new fragments, and sets up destructor to sock_wfree. IOW, we have no choice but to fix up sk_wmem accouting to reflect the fully reassembled skb, else wmem will underflow. This change moves the orphan down into the core, to last possible moment. As ip_defrag_offset is aliased with sk_buff->sk member, we must move the offset into the FRAG_CB, else skb->sk gets clobbered. This allows to delay the orphaning long enough to learn if the skb has to be queued or if the skb is completing the reasm queue. In the former case, things work as before, skb is orphaned. This is safe because skb gets queued/stolen and won't continue past reasm engine. In the latter case, we will steal the skb->sk reference, reattach it to the head skb, and fix up wmem accouting when inet_frag inflates truesize. Fixes: 7026b1ddb6b8 ("netfilter: Pass socket pointer down through okfn().") Diagnosed-by: Eric Dumazet Reported-by: xingwei lee Reported-by: yue sun Reported-by: syzbot+e5167d7144a62715044c@syzkaller.appspotmail.com Signed-off-by: Florian Westphal Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20240326101845.30836-1-fw@strlen.de Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net: esp: fix bad handling of pages from page_pool

2024-04-03T13:28:35+00:00

[ Upstream commit c3198822c6cb9fb588e446540485669cc81c5d34 ] When the skb is reorganized during esp_output (!esp->inline), the pages coming from the original skb fragments are supposed to be released back to the system through put_page. But if the skb fragment pages are originating from a page_pool, calling put_page on them will trigger a page_pool leak which will eventually result in a crash. This leak can be easily observed when using CONFIG_DEBUG_VM and doing ipsec + gre (non offloaded) forwarding: BUG: Bad page state in process ksoftirqd/16 pfn:1451b6 page:00000000de2b8d32 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1451b6000 pfn:0x1451b6 flags: 0x200000000000000(node=0|zone=2) page_type: 0xffffffff() raw: 0200000000000000 dead000000000040 ffff88810d23c000 0000000000000000 raw: 00000001451b6000 0000000000000001 00000000ffffffff 0000000000000000 page dumped because: page_pool leak Modules linked in: ip_gre gre mlx5_ib mlx5_core xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink iptable_nat nf_nat xt_addrtype br_netfilter rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi ib_umad rdma_cm ib_ipoib iw_cm ib_cm ib_uverbs ib_core overlay zram zsmalloc fuse [last unloaded: mlx5_core] CPU: 16 PID: 96 Comm: ksoftirqd/16 Not tainted 6.8.0-rc4+ #22 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x36/0x50 bad_page+0x70/0xf0 free_unref_page_prepare+0x27a/0x460 free_unref_page+0x38/0x120 esp_ssg_unref.isra.0+0x15f/0x200 esp_output_tail+0x66d/0x780 esp_xmit+0x2c5/0x360 validate_xmit_xfrm+0x313/0x370 ? validate_xmit_skb+0x1d/0x330 validate_xmit_skb_list+0x4c/0x70 sch_direct_xmit+0x23e/0x350 __dev_queue_xmit+0x337/0xba0 ? nf_hook_slow+0x3f/0xd0 ip_finish_output2+0x25e/0x580 iptunnel_xmit+0x19b/0x240 ip_tunnel_xmit+0x5fb/0xb60 ipgre_xmit+0x14d/0x280 [ip_gre] dev_hard_start_xmit+0xc3/0x1c0 __dev_queue_xmit+0x208/0xba0 ? nf_hook_slow+0x3f/0xd0 ip_finish_output2+0x1ca/0x580 ip_sublist_rcv_finish+0x32/0x40 ip_sublist_rcv+0x1b2/0x1f0 ? ip_rcv_finish_core.constprop.0+0x460/0x460 ip_list_rcv+0x103/0x130 __netif_receive_skb_list_core+0x181/0x1e0 netif_receive_skb_list_internal+0x1b3/0x2c0 napi_gro_receive+0xc8/0x200 gro_cell_poll+0x52/0x90 __napi_poll+0x25/0x1a0 net_rx_action+0x28e/0x300 __do_softirq+0xc3/0x276 ? sort_range+0x20/0x20 run_ksoftirqd+0x1e/0x30 smpboot_thread_fn+0xa6/0x130 kthread+0xcd/0x100 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x31/0x50 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork_asm+0x11/0x20 The suggested fix is to introduce a new wrapper (skb_page_unref) that covers page refcounting for page_pool pages as well. Cc: stable@vger.kernel.org Fixes: 6a5bcd84e886 ("page_pool: Allow drivers to hint on SKB recycling") Reported-and-tested-by: Anatoli N.Chechelnickiy Reported-by: Ian Kumlien Link: https://lore.kernel.org/netdev/CAA85sZvvHtrpTQRqdaOx6gd55zPAVsqMYk_Lwh4Md5knTq7AyA@mail.gmail.com Signed-off-by: Dragos Tatulea Reviewed-by: Mina Almasry Reviewed-by: Jakub Kicinski Acked-by: Ilias Apalodimas Signed-off-by: Steffen Klassert Signed-off-by: Sasha Levin