kernel/linux.git/net/hsr, branch v6.6.131

net/hsr: fix NULL pointer dereference in prp_get_untagged_frame()

2026-01-11T14:21:50+00:00

commit 188e0fa5a679570ea35474575e724d8211423d17 upstream. prp_get_untagged_frame() calls __pskb_copy() to create frame->skb_std but doesn't check if the allocation failed. If __pskb_copy() returns NULL, skb_clone() is called with a NULL pointer, causing a crash: Oops: general protection fault, probably for non-canonical address 0xdffffc000000000f: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000078-0x000000000000007f] CPU: 0 UID: 0 PID: 5625 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:skb_clone+0xd7/0x3a0 net/core/skbuff.c:2041 Code: 03 42 80 3c 20 00 74 08 4c 89 f7 e8 23 29 05 f9 49 83 3e 00 0f 85 a0 01 00 00 e8 94 dd 9d f8 48 8d 6b 7e 49 89 ee 49 c1 ee 03 <43> 0f b6 04 26 84 c0 0f 85 d1 01 00 00 44 0f b6 7d 00 41 83 e7 0c RSP: 0018:ffffc9000d00f200 EFLAGS: 00010207 RAX: ffffffff892235a1 RBX: 0000000000000000 RCX: ffff88803372a480 RDX: 0000000000000000 RSI: 0000000000000820 RDI: 0000000000000000 RBP: 000000000000007e R08: ffffffff8f7d0f77 R09: 1ffffffff1efa1ee R10: dffffc0000000000 R11: fffffbfff1efa1ef R12: dffffc0000000000 R13: 0000000000000820 R14: 000000000000000f R15: ffff88805144cc00 FS: 0000555557f6d500(0000) GS:ffff88808d72f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000555581d35808 CR3: 000000005040e000 CR4: 0000000000352ef0 Call Trace: hsr_forward_do net/hsr/hsr_forward.c:-1 [inline] hsr_forward_skb+0x1013/0x2860 net/hsr/hsr_forward.c:741 hsr_handle_frame+0x6ce/0xa70 net/hsr/hsr_slave.c:84 __netif_receive_skb_core+0x10b9/0x4380 net/core/dev.c:5966 __netif_receive_skb_one_core net/core/dev.c:6077 [inline] __netif_receive_skb+0x72/0x380 net/core/dev.c:6192 netif_receive_skb_internal net/core/dev.c:6278 [inline] netif_receive_skb+0x1cb/0x790 net/core/dev.c:6337 tun_rx_batched+0x1b9/0x730 drivers/net/tun.c:1485 tun_get_user+0x2b65/0x3e90 drivers/net/tun.c:1953 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1999 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0449f8e1ff Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48 RSP: 002b:00007ffd7ad94c90 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f044a1e5fa0 RCX: 00007f0449f8e1ff RDX: 000000000000003e RSI: 0000200000000500 RDI: 00000000000000c8 RBP: 00007ffd7ad94d20 R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000003e R11: 0000000000000293 R12: 0000000000000001 R13: 00007f044a1e5fa0 R14: 00007f044a1e5fa0 R15: 0000000000000003 Add a NULL check immediately after __pskb_copy() to handle allocation failures gracefully. Reported-by: syzbot+2fa344348a579b779e05@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=2fa344348a579b779e05 Fixes: f266a683a480 ("net/hsr: Better frame dispatch") Cc: stable@vger.kernel.org Signed-off-by: Shaurya Rane Reviewed-by: Felix Maurer Tested-by: Felix Maurer Link: https://patch.msgid.link/20251129093718.25320-1-ssrane_b23@ee.vjti.ac.in Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

hsr: Fix supervision frame sending on HSRv0

2025-11-24T09:30:01+00:00

[ Upstream commit 96a3a03abf3d8cc38cd9cb0d280235fbcf7c3f7f ] On HSRv0, no supervision frames were sent. The supervison frames were generated successfully, but failed the check for a sufficiently long mac header, i.e., at least sizeof(struct hsr_ethhdr), in hsr_fill_frame_info() because the mac header only contained the ethernet header. Fix this by including the HSR header in the mac header when generating HSR supervision frames. Note that the mac header now also includes the TLV fields. This matches how we set the headers on rx and also the size of struct hsrv0_ethhdr_sp. Reported-by: Hangbin Liu Closes: https://lore.kernel.org/netdev/aMONxDXkzBZZRfE5@fedora/ Fixes: 9cfb5e7f0ded ("net: hsr: fix hsr_init_sk() vs network/transport headers.") Signed-off-by: Felix Maurer Reviewed-by: Sebastian Andrzej Siewior Tested-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/4354114fea9a642fe71f49aeeb6c6159d1d61840.1762876095.git.fmaurer@redhat.com Tested-by: Hangbin Liu Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

hsr: use hsr_for_each_port_rtnl in hsr_port_get_hsr

2025-09-19T14:32:06+00:00

[ Upstream commit 393c841fe4333cdd856d0ca37b066d72746cfaa6 ] hsr_port_get_hsr() iterates over ports using hsr_for_each_port(), but many of its callers do not hold the required RCU lock. Switch to hsr_for_each_port_rtnl(), since most callers already hold the rtnl lock. After review, all callers are covered by either the rtnl lock or the RCU lock, except hsr_dev_xmit(). Fix this by adding an RCU read lock there. Fixes: c5a759117210 ("net/hsr: Use list_head (and rcu) instead of array for slave devices.") Signed-off-by: Hangbin Liu Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250905091533.377443-3-liuhangbin@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

hsr: use rtnl lock when iterating over ports

2025-09-19T14:32:06+00:00

[ Upstream commit 8884c693991333ae065830554b9b0c96590b1bb2 ] hsr_for_each_port is called in many places without holding the RCU read lock, this may trigger warnings on debug kernels. Most of the callers are actually hold rtnl lock. So add a new helper hsr_for_each_port_rtnl to allow callers in suitable contexts to iterate ports safely without explicit RCU locking. This patch only fixed the callers that is hold rtnl lock. Other caller issues will be fixed in later patches. Fixes: c5a759117210 ("net/hsr: Use list_head (and rcu) instead of array for slave devices.") Signed-off-by: Hangbin Liu Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250905091533.377443-2-liuhangbin@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net: hsr: Add VLAN CTAG filter support

2025-09-19T14:32:06+00:00

[ Upstream commit 1a8a63a5305e95519de6f941922dfcd8179f82e5 ] This patch adds support for VLAN ctag based filtering at slave devices. The slave ethernet device may be capable of filtering ethernet packets based on VLAN ID. This requires that when the VLAN interface is created over an HSR/PRP interface, it passes the VID information to the associated slave ethernet devices so that it updates the hardware filters to filter ethernet frames based on VID. This patch adds the required functions to propagate the vid information to the slave devices. Signed-off-by: Murali Karicheri Signed-off-by: MD Danish Anwar Reviewed-by: Jiri Pirko Link: https://patch.msgid.link/20241106091710.3308519-3-danishanwar@ti.com Signed-off-by: Jakub Kicinski Stable-dep-of: 8884c6939913 ("hsr: use rtnl lock when iterating over ports") Signed-off-by: Sasha Levin

net: hsr: Add support for MC filtering at the slave device

2025-09-19T14:32:06+00:00

[ Upstream commit 36b20fcdd9663ced36d3aef96f0eff8eb79de4b8 ] When MC (multicast) list is updated by the networking layer due to a user command and as well as when allmulti flag is set, it needs to be passed to the enslaved Ethernet devices. This patch allows this to happen by implementing ndo_change_rx_flags() and ndo_set_rx_mode() API calls that in turns pass it to the slave devices using existing API calls. Signed-off-by: Murali Karicheri Signed-off-by: Ravi Gunasekaran Reviewed-by: Wojciech Drewek Reviewed-by: Simon Horman Signed-off-by: David S. Miller Stable-dep-of: 8884c6939913 ("hsr: use rtnl lock when iterating over ports") Signed-off-by: Sasha Levin

net, hsr: reject HSR frame if skb can't hold tag

2025-08-28T14:28:39+00:00

commit 7af76e9d18a9fd6f8611b3313c86c190f9b6a5a7 upstream. Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 #12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 [ 45.402911] Call Trace: [ 45.403105] [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: stable@kernel.org Fixes: 48b491a5cc74 ("net: hsr: fix mac_len checks") Reported-by: syzbot+a81f2759d022496b40ab@syzkaller.appspotmail.com Signed-off-by: Jakub Acs Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250819082842.94378-1-acsjakub@amazon.de Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: hsr: fix fill_frame_info() regression vs VLAN packets

2025-02-08T08:52:32+00:00

[ Upstream commit 0f5697f1a3f99bc2b674b8aa3c5da822c5673c11 ] Stephan Wurm reported that my recent patch broke VLAN support. Apparently skb->mac_len is not correct for VLAN traffic as shown by debug traces [1]. Use instead pskb_may_pull() to make sure the expected header is present in skb->head. Many thanks to Stephan for his help. [1] kernel: skb len=170 headroom=2 headlen=170 tailroom=20 mac=(2,14) mac_len=14 net=(16,-1) trans=-1 shinfo(txflags=0 nr_frags=0 gso(size=0 type=0 segs=0)) csum(0x0 start=0 offset=0 ip_summed=0 complete_sw=0 valid=0 level=0) hash(0x0 sw=0 l4=0) proto=0x0000 pkttype=0 iif=0 priority=0x0 mark=0x0 alloc_cpu=0 vlan_all=0x0 encapsulation=0 inner(proto=0x0000, mac=0, net=0, trans=0) kernel: dev name=prp0 feat=0x0000000000007000 kernel: sk family=17 type=3 proto=0 kernel: skb headroom: 00000000: 74 00 kernel: skb linear: 00000000: 01 0c cd 01 00 01 00 d0 93 53 9c cb 81 00 80 00 kernel: skb linear: 00000010: 88 b8 00 01 00 98 00 00 00 00 61 81 8d 80 16 52 kernel: skb linear: 00000020: 45 47 44 4e 43 54 52 4c 2f 4c 4c 4e 30 24 47 4f kernel: skb linear: 00000030: 24 47 6f 43 62 81 01 14 82 16 52 45 47 44 4e 43 kernel: skb linear: 00000040: 54 52 4c 2f 4c 4c 4e 30 24 44 73 47 6f 6f 73 65 kernel: skb linear: 00000050: 83 07 47 6f 49 64 65 6e 74 84 08 67 8d f5 93 7e kernel: skb linear: 00000060: 76 c8 00 85 01 01 86 01 00 87 01 00 88 01 01 89 kernel: skb linear: 00000070: 01 00 8a 01 02 ab 33 a2 15 83 01 00 84 03 03 00 kernel: skb linear: 00000080: 00 91 08 67 8d f5 92 77 4b c6 1f 83 01 00 a2 1a kernel: skb linear: 00000090: a2 06 85 01 00 83 01 00 84 03 03 00 00 91 08 67 kernel: skb linear: 000000a0: 8d f5 92 77 4b c6 1f 83 01 00 kernel: skb tailroom: 00000000: 80 18 02 00 fe 4e 00 00 01 01 08 0a 4f fd 5e d1 kernel: skb tailroom: 00000010: 4f fd 5e cd Fixes: b9653d19e556 ("net: hsr: avoid potential out-of-bound access in fill_frame_info()") Reported-by: Stephan Wurm Tested-by: Stephan Wurm Closes: https://lore.kernel.org/netdev/Z4o_UC0HweBHJ_cw@PC-LX-SteWu/ Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250129130007.644084-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: hsr: avoid potential out-of-bound access in fill_frame_info()

2024-12-14T18:59:34+00:00

[ Upstream commit b9653d19e556c6afd035602927a93d100a0d7644 ] syzbot is able to feed a packet with 14 bytes, pretending it is a vlan one. Since fill_frame_info() is relying on skb->mac_len already, extend the check to cover this case. BUG: KMSAN: uninit-value in fill_frame_info net/hsr/hsr_forward.c:709 [inline] BUG: KMSAN: uninit-value in hsr_forward_skb+0x9ee/0x3b10 net/hsr/hsr_forward.c:724 fill_frame_info net/hsr/hsr_forward.c:709 [inline] hsr_forward_skb+0x9ee/0x3b10 net/hsr/hsr_forward.c:724 hsr_dev_xmit+0x2f0/0x350 net/hsr/hsr_device.c:235 __netdev_start_xmit include/linux/netdevice.h:5002 [inline] netdev_start_xmit include/linux/netdevice.h:5011 [inline] xmit_one net/core/dev.c:3590 [inline] dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3606 __dev_queue_xmit+0x366a/0x57d0 net/core/dev.c:4434 dev_queue_xmit include/linux/netdevice.h:3168 [inline] packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276 packet_snd net/packet/af_packet.c:3146 [inline] packet_sendmsg+0x91ae/0xa6f0 net/packet/af_packet.c:3178 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:726 __sys_sendto+0x594/0x750 net/socket.c:2197 __do_sys_sendto net/socket.c:2204 [inline] __se_sys_sendto net/socket.c:2200 [inline] __x64_sys_sendto+0x125/0x1d0 net/socket.c:2200 x64_sys_call+0x346a/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:45 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Uninit was created at: slab_post_alloc_hook mm/slub.c:4091 [inline] slab_alloc_node mm/slub.c:4134 [inline] kmem_cache_alloc_node_noprof+0x6bf/0xb80 mm/slub.c:4186 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:587 __alloc_skb+0x363/0x7b0 net/core/skbuff.c:678 alloc_skb include/linux/skbuff.h:1323 [inline] alloc_skb_with_frags+0xc8/0xd00 net/core/skbuff.c:6612 sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2881 packet_alloc_skb net/packet/af_packet.c:2995 [inline] packet_snd net/packet/af_packet.c:3089 [inline] packet_sendmsg+0x74c6/0xa6f0 net/packet/af_packet.c:3178 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:726 __sys_sendto+0x594/0x750 net/socket.c:2197 __do_sys_sendto net/socket.c:2204 [inline] __se_sys_sendto net/socket.c:2200 [inline] __x64_sys_sendto+0x125/0x1d0 net/socket.c:2200 x64_sys_call+0x346a/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:45 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: 48b491a5cc74 ("net: hsr: fix mac_len checks") Reported-by: syzbot+671e2853f9851d039551@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6745dc7f.050a0220.21d33d.0018.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Cc: WingMan Kwok Cc: Murali Karicheri Cc: MD Danish Anwar Cc: Jiri Pirko Cc: George McCollister Link: https://patch.msgid.link/20241126144344.4177332-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: hsr: fix hsr_init_sk() vs network/transport headers.

2024-12-09T09:32:34+00:00

[ Upstream commit 9cfb5e7f0ded2bfaabc270ceb5f91d13f0e805b9 ] Following sequence in hsr_init_sk() is invalid : skb_reset_mac_header(skb); skb_reset_mac_len(skb); skb_reset_network_header(skb); skb_reset_transport_header(skb); It is invalid because skb_reset_mac_len() needs the correct network header, which should be after the mac header. This patch moves the skb_reset_network_header() and skb_reset_transport_header() before the call to dev_hard_header(). As a result skb->mac_len is no longer set to a value close to 65535. Fixes: 48b491a5cc74 ("net: hsr: fix mac_len checks") Signed-off-by: Eric Dumazet Cc: George McCollister Link: https://patch.msgid.link/20241122171343.897551-1-edumazet@google.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin