In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
fou: reject omitted FOU_ATTR_IPPROTO on FOU_ENCAP_DIRECT<\/p>\n
Commit 7a9bc9e3f423 (“fou: Don’t allow 0 for FOU_ATTR_IPPROTO.”) added
\nNLA_POLICY_MIN(NLA_U8, 1) to fou_nl_policy[FOU_ATTR_IPPROTO], which
\nrejects an explicitly supplied FOU_ATTR_IPPROTO == 0 attribute with
\n-ERANGE.<\/p>\n
However, FOU_ATTR_IPPROTO is an optional netlink attribute. When a user
\nsends FOU_CMD_ADD with FOU_ATTR_TYPE set to FOU_ENCAP_DIRECT and omits
\nFOU_ATTR_IPPROTO entirely, nla_policy validation succeeds and
\nparse_nl_config() leaves cfg->protocol as 0 (from memset(cfg, 0,
\nsizeof(*cfg))). fou_create() then creates a FOU_ENCAP_DIRECT socket with
\nfou->protocol == 0.<\/p>\n
In fou_udp_recv(), returning -fou->protocol to udp_queue_rcv_one_skb()
\ntriggers IP protocol resubmission when fou->protocol > 0, whereas
\nreturning 0 tells the UDP tunnel layer that the skb was consumed without
\nfreeing it. When fou->protocol == 0, every packet received on the socket
\nreturns 0 from fou_udp_recv() and leaks the sk_buff.<\/p>\n
Reject FOU_ENCAP_DIRECT when !cfg->protocol in fou_create() so that
\ncreating a direct encapsulation port without FOU_ATTR_IPPROTO fails with
\n-EINVAL while leaving FOU_CMD_DEL and FOU_CMD_GET (which share
\nparse_nl_config()) unaffected.<\/p>\n
Tested in QEMU against Linux 7.3.0-rc3 by sending a FOU_CMD_ADD Generic
\nNetlink request with FOU_ATTR_PORT = 5555 and FOU_ATTR_TYPE =
\nFOU_ENCAP_DIRECT while omitting FOU_ATTR_IPPROTO. On the unfixed kernel,
\nFOU_CMD_ADD succeeds (err = 0), FOU_CMD_GET reports fou->type = 1 and
\nfou->protocol = 0, and sending 4000 UDP packets to 127.0.0.1:5555 leaks
\nall 4000 sk_buffs (SUnreclaim in \/proc\/meminfo grows from 41456 kB to
\n59008 kB, +17552 kB); with this patch applied, FOU_CMD_ADD is rejected
\nwith -EINVAL (-22).<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
fou: reject omitted FOU_ATTR_IPPROTO on FOU_ENCAP_DIRECT<\/p>\n
Commit 7a9bc9e3f423 (“fou: Don’t allow 0 for FOU_ATTR_IPPROTO.”) added
\nNL<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-41013","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/41013","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=41013"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41013"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41013"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}