6.12-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ 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 stephan.wurm@a-eberle.de Tested-by: Stephan Wurm stephan.wurm@a-eberle.de Closes: https://lore.kernel.org/netdev/Z4o_UC0HweBHJ_cw@PC-LX-SteWu/ Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Simon Horman horms@kernel.org Link: https://patch.msgid.link/20250129130007.644084-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/hsr/hsr_forward.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c index 40c5fbbd155d6..c0217476eb17f 100644 --- a/net/hsr/hsr_forward.c +++ b/net/hsr/hsr_forward.c @@ -688,9 +688,12 @@ static int fill_frame_info(struct hsr_frame_info *frame, frame->is_vlan = true;
if (frame->is_vlan) { - if (skb->mac_len < offsetofend(struct hsr_vlan_ethhdr, vlanhdr)) + /* Note: skb->mac_len might be wrong here. */ + if (!pskb_may_pull(skb, + skb_mac_offset(skb) + + offsetofend(struct hsr_vlan_ethhdr, vlanhdr))) return -EINVAL; - vlan_hdr = (struct hsr_vlan_ethhdr *)ethhdr; + vlan_hdr = (struct hsr_vlan_ethhdr *)skb_mac_header(skb); proto = vlan_hdr->vlanhdr.h_vlan_encapsulated_proto; /* FIXME: */ netdev_warn_once(skb->dev, "VLAN not yet supported");