In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
net\/sched: act_ct: fix sk_buff leak when the header checks reject a packet<\/p>\n
tcf_ct_handle_fragments() runs its header sanity checks before handing
\nanything to the defragmentation engine:<\/p>\n
\tif (family == NFPROTO_IPV4)
\n\t\terr = tcf_ct_ipv4_is_fragment(skb, &frag);
\n\telse
\n\t\terr = tcf_ct_ipv6_is_fragment(skb, &frag);
\n\tif (err || !frag)
\n\t\treturn err;<\/p>\n
tcf_ct_ipv4_is_fragment() returns -EINVAL or -ENOMEM;
\ntcf_ct_ipv6_is_fragment() adds -EPROTO when ipv6_find_hdr() fails. None of
\nthem frees or queues the skb, so on that path the caller still owns it.<\/p>\n
tcf_ct_act() however funnels every non-zero return into the
\nownership-transfer exit:<\/p>\n
\terr = tcf_ct_handle_fragments(net, skb, family, p->zone, &defrag);
\n\tif (err)
\n\t\tgoto out_frag;
\n\t…
\nout_frag:
\n\tif (err != -EINPROGRESS)
\n\t\ttcf_action_inc_drop_qstats(&c->common);
\n\treturn TC_ACT_CONSUMED;<\/p>\n
TC_ACT_CONSUMED means the action took ownership of the skb, so no caller
\nfrees it – sch_handle_ingress(), sch_handle_egress() and
\ntcf_qevent_handle() all deliberately skip the free for that verdict. The
\nskb is therefore orphaned: one sk_buff plus its data buffer is leaked per
\nmalformed packet, unbounded. Note the drop counter is already incremented
\nfor these errors, so the statistics claim a drop that never happens.<\/p>\n
Three different ownership states reach out_frag: today – the skb may be
\nqueued by the defrag engine (-EINPROGRESS), already freed by
\nnf_ct_handle_fragments(), or still owned by us. Tell the caller which of
\nthose it is, and free the packet ourselves in the last case, which
\nrestores the TC_ACT_SHOT behaviour that predated the Fixes: commit.<\/p>\n
Reproduced on v7.2-rc6 with a 54-byte frame carrying a 40-byte IPv6
\nheader with nexthdr = 0 (hop-by-hop) and nothing after it, on a
\nclsact ingress chain with “action ct”. kmemleak reports one leaked
\n232-byte skbuff_head_cache object plus its 704-byte data buffer per
\npacket; with this patch it reports none.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
net\/sched: act_ct: fix sk_buff leak when the header checks reject a packet<\/p>\n
tcf_ct_handle_fragments() runs its header sanity checks<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-11224","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/11224","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=11224"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11224"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11224"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}