In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
openvswitch: only skb_tx_error() a packet we are about to drop<\/p>\n
queue_userspace_packet() borrows the packet skb — it only copies it into
\na private netlink message (user_skb) and does not own it; on return
\ndo_execute_actions() keeps forwarding it through the flow’s remaining
\nactions. Its error path nevertheless calls skb_tx_error(skb), which via
\nskb_zcopy_clear() does skb_shinfo(skb)->flags &= ~SKBFL_ALL_ZEROCOPY,
\nstripping SKBFL_SHARED_FRAG from that live skb (skb_tx_error()’s kerneldoc
\nsays “skb must be freed afterwards”).<\/p>\n
For a MSG_ZEROCOPY skb carrying page-cache frags, SKBFL_SHARED_FRAG is
\nwhat makes esp_input() skb_cow_data() before in-place AEAD; once it is
\nstripped a later local ESP-in-UDP delivery decrypts in place over pages
\nthe sender does not own — an unprivileged page-cache write (the
\n“Fragnesia” primitive).
\ndo_execute_actions() ignores output_userspace()’s return value, so any
\naction after a failed USERSPACE upcall inherits the stripped skb.<\/p>\n
Move the skb_tx_error() to the flow-miss drop path – the “default”
\nbranch of ovs_dp_process_packet()’s switch(error), before kfree_skb().<\/p>\n
The call has been here since commit 36d5fe6a0007 (“core, nfqueue,
\nopenvswitch: Orphan frags in skb_zerocopy and handle errors”) but was
\nharmless until esp_input() began relying on SKBFL_SHARED_FRAG to gate
\nin-place decrypt; only then did stripping it on a still-forwarded skb
\nbecome a page-cache write primitive.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
openvswitch: only skb_tx_error() a packet we are about to drop<\/p>\n
queue_userspace_packet() borrows the packet skb — it only copies i<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-21409","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/21409","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=21409"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21409"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21409"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}