{"id":"CVE-2026-64269","summary":"RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg\n\nWhen the server answers an RTRS READ, rdma_write_sg() builds the source\nscatter/gather entry for the IB_WR_RDMA_WRITE that returns data to the\npeer. Its length is taken directly from the wire descriptor:\n\n  plist-\u003elength = le32_to_cpu(id-\u003erd_msg-\u003edesc[0].len);\n\nrd_msg points into the chunk buffer that the remote peer filled via\nRDMA-WRITE-WITH-IMM (rtrs_srv_rdma_done() -\u003e process_io_req() -\u003e\nprocess_read()), so desc[0].len is attacker-controlled and, before this\nchange, was only rejected when zero. The source address is the fixed\nchunk start (dma_addr[msg_id]) and the source lkey is the PD-wide\nlocal_dma_lkey, which is not tied to the chunk's MR mapping, so the verbs\nlayer does not constrain the transfer length to max_chunk_size. msg_id\nand off are bounded against queue_depth and max_chunk_size in\nrtrs_srv_rdma_done(), but desc[0].len is a separate field that was not\nchecked against the chunk size.\n\nA peer that advertises desc[0].len larger than max_chunk_size can make\nthe posted RDMA write read past the chunk's mapped region. The resulting\nbehaviour depends on the IOMMU configuration: with no IOMMU or in\npassthrough mode the read may extend into memory adjacent to the chunk\nand be returned to the peer, which can disclose host memory; with a\ntranslating IOMMU the out-of-range access is expected to fault and abort\nthe connection. In either case the transfer exceeds what the protocol\npermits and is driven by a remote peer.\n\nReject a descriptor length above max_chunk_size, mirroring the existing\noff \u003e= max_chunk_size bound in rtrs_srv_rdma_done(). Legitimate clients\ndo not exceed it: the client sets desc[0].len to its MR length, which is\ncapped at the negotiated max_io_size (max_chunk_size - MAX_HDR_SIZE).","modified":"2026-07-27T04:03:20.881902860Z","published":"2026-07-25T08:49:16.946Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64269.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2912f3d40355dabc08fdbaaf2764d02445fe88dc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5a45d0aa1fa50a333ce5763ade744e2d89838667"},{"type":"WEB","url":"https://git.kernel.org/stable/c/68c09762172f6224e9ddf9b0a60bacbb36e443eb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6cada540150894e81042a0ae0c796a21a9a877da"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6f40246f4312fdbab5a13cc440adebf95eb2aa66"},{"type":"WEB","url":"https://git.kernel.org/stable/c/963af8d97a8c6a117134a8d0db1415e0489200b1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/da3e44add94b05dfde56f898421922f5cf35705f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64269.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64269"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"9cb837480424e78ed585376f944088246685aec3"},{"fixed":"68c09762172f6224e9ddf9b0a60bacbb36e443eb"},{"fixed":"6cada540150894e81042a0ae0c796a21a9a877da"},{"fixed":"2912f3d40355dabc08fdbaaf2764d02445fe88dc"},{"fixed":"6f40246f4312fdbab5a13cc440adebf95eb2aa66"},{"fixed":"5a45d0aa1fa50a333ce5763ade744e2d89838667"},{"fixed":"da3e44add94b05dfde56f898421922f5cf35705f"},{"fixed":"963af8d97a8c6a117134a8d0db1415e0489200b1"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64269.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.8.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64269.json"}}],"schema_version":"1.7.5"}