In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
vlan: require the MAC header to be present in __vlan_insert_inner_tag()<\/p>\n
__vlan_insert_inner_tag() only guarantees head room via skb_cow_head(),
\nnever that mac_len bytes of MAC header are present. Its ETH_HLEN
\nwrappers – __vlan_insert_tag() under skb_vlan_push(), and
\nvlan_insert_tag() under validate_xmit_vlan() on the generic transmit
\npath – therefore rewrite the first 16 bytes at skb->data: a 12-byte
\nmemmove plus two 2-byte stores at +12 and +14. No caller supplies the
\nbound, while the pop helpers use skb_ensure_writable()\/pskb_may_pull().<\/p>\n
An IFF_TUN device has hard_header_len == 0, so packet_snd() accepts a
\none-byte AF_PACKET\/SOCK_RAW frame. The first vlan push only sets a
\nhwaccel tag; the next – clsact “action vlan push” or
\nbpf_skb_vlan_push() – enters the helper with skb->len still 1. The
\nhead comes from skbuff_small_head without __GFP_ZERO, so each push
\ndrags bytes from beyond skb->tail into the frame. After three the
\none-byte send leaves as 13 bytes carrying 11 bytes of uninitialised
\nslab:<\/p>\n
0000: 5a b3 62 12 80 88 ff ff 00 b3 62 12 81
\n `——————————‘
\n only 0x5a was sent; the rest is slab, here the top 56 bits of a
\n linear-map address<\/p>\n
Require the MAC header the helper rewrites to be present, so such a
\nframe is dropped rather than transmitted.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
vlan: require the MAC header to be present in __vlan_insert_inner_tag()<\/p>\n
__vlan_insert_inner_tag() only guarantees head room via sk<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-34940","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/34940","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=34940"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=34940"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=34940"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}