In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
svcrdma: Reject Write\/Reply chunks with segcount 0<\/p>\n
A peer can send a Write or Reply chunk whose segcount field is zero.
\nxdr_check_write_chunk() only rejects segcount > rc_maxpages, so zero
\npasses the range check, and xdr_inline_decode(stream, 0) returns the
\ncurrent (non-NULL) cursor without advancing. The function returns
\ntrue and pcl_alloc_write() then links a struct svc_rdma_chunk with
\nch_segcount == 0 onto rc_write_pcl or rc_reply_pcl.<\/p>\n
An earlier patch in this series made pcl_for_each_segment() safe for
\nch_segcount == 0, so this no longer drives the memory walk it used
\nto. Rejecting the malformed frame at the decode boundary is still
\nworthwhile as defense in depth: it keeps degenerate zero-segment
\nchunks off the parsed chunk lists entirely, so any future consumer
\nthat walks ch_segments directly cannot observe one, and it makes the
\nzero-floor easy to backport to trees where the macro change is more
\nintrusive. RFC 8166 has no meaning for a Write\/Reply chunk that
\ndescribes no remote buffer, so no legitimate client is affected.<\/p>\n
xdr_check_reply_chunk() funnels Reply chunks through
\nxdr_check_write_chunk() and inherits the same rejection.<\/p>\n
pcl_alloc_write() also links each chunk onto the parsed chunk list
\nbefore filling its segment array. If a future change weakens the
\nsegcount-0 rejection, an incomplete chunk is visible to consumers
\nduring the fill loop. Reorder so that list_add_tail() follows the
\nsegment fill loop, ensuring only fully-populated chunks appear on
\nthe list.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
svcrdma: Reject Write\/Reply chunks with segcount 0<\/p>\n
A peer can send a Write or Reply chunk whose segcount field is zero.
\nxdr_check_<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-28492","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/28492","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=28492"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28492"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28492"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}