In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
xen\/pvcalls: bound backend response req_id before indexing rsp[]<\/p>\n
pvcalls_front_event_handler() takes req_id directly from the
\nbackend-supplied ring response and uses it to index the fixed-size
\nbedata->rsp[] array for a memcpy() and a store, with no range check. A
\nmalicious or buggy backend can set req_id past PVCALLS_NR_RSP_PER_RING
\nand drive an out-of-bounds write past the bedata allocation.<\/p>\n
req_id was also declared int while the wire field rsp->req_id is u32, so
\na range check on the signed value alone is insufficient: a backend
\nreq_id of 0xffffffff becomes -1, passes a >= PVCALLS_NR_RSP_PER_RING
\ntest and indexes bedata->rsp[-1]. Declare req_id as u32 so a single
\nbound covers both ends.<\/p>\n
A backend that sends an out-of-range req_id has violated the wire
\nprotocol, so rather than silently dropping the response, log once and
\nstop trusting the backend: set bedata->disabled. The event handler then
\nignores further responses, and the request paths that wait for a
\nresponse return -EIO instead of blocking forever. This mirrors the
\nfatal-error handling xen-netback uses (xenvif_fatal_tx_err()).<\/p>\n
The pvcalls frontend currently trusts its backend, so this is not a
\nclassic-Xen security issue, but it matters for hardening PV frontends
\nagainst malicious backends (confidential and disaggregated deployments).<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
xen\/pvcalls: bound backend response req_id before indexing rsp[]<\/p>\n
pvcalls_front_event_handler() takes req_id directly from the
\nback<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-7023","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/7023","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=7023"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7023"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7023"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}