In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
svcrdma: Fix pcl_for_each_segment for empty chunks<\/p>\n
When a parsed chunk list contains a chunk whose ch_segcount is zero,
\npcl_for_each_segment computes its inclusive upper bound as
\n&chunk->ch_segments[ch_segcount – 1]. ch_segcount is u32, so the
\nsubtraction wraps to 0xFFFFFFFF and the bound lands far past the
\nch_segments flex array. The loop body then walks unrelated memory at
\nsizeof(struct svc_rdma_segment) stride until it faults.<\/p>\n
A zero-segcount chunk is reachable from the wire:
\nxdr_check_write_chunk() only rejects segcount values greater than
\nrc_maxpages, and pcl_alloc_write() links a freshly allocated chunk
\nonto rc_write_pcl\/rc_reply_pcl before its segment-fill loop runs,
\nso a Write or Reply chunk advertising zero segments leaves
\nch_segcount == 0 on the list. When the transport has negotiated
\nSend-With-Invalidate, svc_rdma_get_inv_rkey() iterates all four
\nPCLs with pcl_for_each_segment and dereferences segment->rs_handle
\non each iteration, turning the underflow into an out-of-bounds read
\nand a general protection fault.<\/p>\n
xdr_check_write_list \/ xdr_check_reply_chunk
\n pcl_alloc_write()
\n chunk = pcl_alloc_chunk(…) \/* ch_segcount = 0 *\/
\n list_add_tail(&chunk->ch_list, &pcl->cl_chunks)
\n \/* fill loop iterates zero times for wire segcount 0 *\/<\/p>\n
svc_rdma_get_inv_rkey()
\n pcl_for_each_chunk(rc_write_pcl)
\n pcl_for_each_segment(segment, chunk)
\n pos rs_handle \/* OOB read -> GPF *\/<\/p>\n
Fix by switching the macro to a half-open upper bound that uses
\nch_segcount directly. For ch_segcount == 0 the loop start equals the
\nloop end and the body is skipped; for ch_segcount > 0 the iteration
\nrange is unchanged. All six existing call sites in
\nnet\/sunrpc\/xprtrdma\/svc_rdma_recvfrom.c and
\nnet\/sunrpc\/xprtrdma\/svc_rdma_rw.c remain correct under the new bound,
\nso no caller changes are needed.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
svcrdma: Fix pcl_for_each_segment for empty chunks<\/p>\n
When a parsed chunk list contains a chunk whose ch_segcount is zero,
\npcl_for_ea<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-21454","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/21454","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=21454"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21454"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21454"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}