{"id":"CVE-2026-64102","state":"PUBLISHED","title":"RDMA/siw: Reject MPA FPDU length underflow before signed receive math","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/siw: Reject MPA FPDU length underflow before signed receive math\n\nA malicious connected siw peer can send an iWARP FPDU whose MPA length\nfield (c_hdr->mpa_len, 16 bit big-endian, peer-controlled) is smaller\nthan the fixed DDP/RDMAP header for the announced opcode. Soft-iWARP\nparses the full header in siw_get_hdr() based on iwarp_pktinfo[opcode]\n.hdr_len, but never compares mpa_len against that header length.\n\nsiw_tcp_rx_data() then derives\n\n    srx->fpdu_part_rem = be16_to_cpu(mpa_len) - fpdu_part_rcvd\n                         + MPA_HDR_SIZE;\n\nwhere fpdu_part_rcvd equals iwarp_pktinfo[opcode].hdr_len at this\npoint. For a tagged WRITE (hdr_len 16, MPA_HDR_SIZE 2) the smallest\non-wire mpa_len of 0 yields fpdu_part_rem = -14, and any mpa_len below\nhdr_len - MPA_HDR_SIZE underflows to a negative int.\n\nThe signed value then flows into siw_proc_write()/siw_proc_rresp() as\n\n    bytes = min(srx->fpdu_part_rem, srx->skb_new);\n\nis handed to siw_check_mem() as an int len (whose interval check\naddr + len > mem->va + mem->len is satisfied for a valid base when\nlen is negative), and reaches siw_rx_data() -> siw_rx_kva() /\nsiw_rx_umem() -> skb_copy_bits() as a signed copy length. The header\ncopy branch in skb_copy_bits() promotes that to size_t, producing a\nmulti-gigabyte read.\n\nKASAN under a KUnit harness that drives the real kernel TCP receive\npath -- a loopback AF_INET socketpair, the malformed FPDU written via\nkernel_sendmsg, sk_data_ready firing in softirq, tcp_read_sock\ndispatching to siw_tcp_rx_data -- reports:\n\n    BUG: KASAN: use-after-free in skb_copy_bits+0x284/0x480\n    Read of size 4294967295 at addr ffff888...\n    Call Trace:\n     skb_copy_bits\n     siw_rx_kva\n     siw_rx_data\n     siw_check_mem\n     siw_proc_write\n     siw_tcp_rx_data\n     __tcp_read_sock\n     siw_qp_llp_data_ready\n     tcp_data_ready\n     tcp_data_queue\n\nAdd the missing invariant at the earliest point where the peer header\nis fully assembled. iwarp_pktinfo[*].hdr_len - MPA_HDR_SIZE is exactly\nthe value the siw transmitter uses as the minimum mpa_len for each\nopcode (drivers/infiniband/sw/siw/siw_qp.c:33), so this matches the\nprotocol contract. Out-of-range FPDUs terminate the connection with\nTERM_ERROR_LAYER_LLP / LLP_ETYPE_MPA / LLP_ECODE_FPDU_START -- which\nis RFC 5044 Section 8 error code 3 (\"Marker and ULPDU Length fields\ndo not agree on the start of an FPDU\"), the correct framing-error\nclass for this inconsistency.","publishedAt":"2026-07-19T15:40:06.776Z","updatedAt":"2026-10-19T20:28:11.907Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"683f7cfbf514193d63c0efa079f3352bde84c2e0","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"4a331582011d9e8089af8aa2a61ec6b4443bb245","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"33a8b5e971e294ec2a7b74211c545e09efd8e9ac","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"14553be882d9ce91749c9d64041de66e34ad8e70","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"1012896f4225e8f801ff3c1648023845b66dfb11","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"775b4dc9618a99a1fa48b57554041a5dc17e1336","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"0ce1bc9e46ecabe84772bb561e373c0d9876d6f2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/infiniband/sw/siw/siw_qp_rx.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.3","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/infiniband/sw/siw/siw_qp_rx.c"]}],"references":["https://git.kernel.org/stable/c/683f7cfbf514193d63c0efa079f3352bde84c2e0","https://git.kernel.org/stable/c/4a331582011d9e8089af8aa2a61ec6b4443bb245","https://git.kernel.org/stable/c/33a8b5e971e294ec2a7b74211c545e09efd8e9ac","https://git.kernel.org/stable/c/14553be882d9ce91749c9d64041de66e34ad8e70","https://git.kernel.org/stable/c/c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2","https://git.kernel.org/stable/c/1012896f4225e8f801ff3c1648023845b66dfb11","https://git.kernel.org/stable/c/775b4dc9618a99a1fa48b57554041a5dc17e1336","https://git.kernel.org/stable/c/0ce1bc9e46ecabe84772bb561e373c0d9876d6f2"],"weaknesses":["CWE-190"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64102.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64102","state":"PUBLISHED","datePublished":"2026-07-19T15:40:06.776Z","dateUpdated":"2026-10-19T20:28:11.907Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.033Z"},"containers":{"cna":{"title":"RDMA/siw: Reject MPA FPDU length underflow before signed receive math","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/siw: Reject MPA FPDU length underflow before signed receive math\n\nA malicious connected siw peer can send an iWARP FPDU whose MPA length\nfield (c_hdr->mpa_len, 16 bit big-endian, peer-controlled) is smaller\nthan the fixed DDP/RDMAP header for the announced opcode. Soft-iWARP\nparses the full header in siw_get_hdr() based on iwarp_pktinfo[opcode]\n.hdr_len, but never compares mpa_len against that header length.\n\nsiw_tcp_rx_data() then derives\n\n    srx->fpdu_part_rem = be16_to_cpu(mpa_len) - fpdu_part_rcvd\n                         + MPA_HDR_SIZE;\n\nwhere fpdu_part_rcvd equals iwarp_pktinfo[opcode].hdr_len at this\npoint. For a tagged WRITE (hdr_len 16, MPA_HDR_SIZE 2) the smallest\non-wire mpa_len of 0 yields fpdu_part_rem = -14, and any mpa_len below\nhdr_len - MPA_HDR_SIZE underflows to a negative int.\n\nThe signed value then flows into siw_proc_write()/siw_proc_rresp() as\n\n    bytes = min(srx->fpdu_part_rem, srx->skb_new);\n\nis handed to siw_check_mem() as an int len (whose interval check\naddr + len > mem->va + mem->len is satisfied for a valid base when\nlen is negative), and reaches siw_rx_data() -> siw_rx_kva() /\nsiw_rx_umem() -> skb_copy_bits() as a signed copy length. The header\ncopy branch in skb_copy_bits() promotes that to size_t, producing a\nmulti-gigabyte read.\n\nKASAN under a KUnit harness that drives the real kernel TCP receive\npath -- a loopback AF_INET socketpair, the malformed FPDU written via\nkernel_sendmsg, sk_data_ready firing in softirq, tcp_read_sock\ndispatching to siw_tcp_rx_data -- reports:\n\n    BUG: KASAN: use-after-free in skb_copy_bits+0x284/0x480\n    Read of size 4294967295 at addr ffff888...\n    Call Trace:\n     skb_copy_bits\n     siw_rx_kva\n     siw_rx_data\n     siw_check_mem\n     siw_proc_write\n     siw_tcp_rx_data\n     __tcp_read_sock\n     siw_qp_llp_data_ready\n     tcp_data_ready\n     tcp_data_queue\n\nAdd the missing invariant at the earliest point where the peer header\nis fully assembled. iwarp_pktinfo[*].hdr_len - MPA_HDR_SIZE is exactly\nthe value the siw transmitter uses as the minimum mpa_len for each\nopcode (drivers/infiniband/sw/siw/siw_qp.c:33), so this matches the\nprotocol contract. Out-of-range FPDUs terminate the connection with\nTERM_ERROR_LAYER_LLP / LLP_ETYPE_MPA / LLP_ECODE_FPDU_START -- which\nis RFC 5044 Section 8 error code 3 (\"Marker and ULPDU Length fields\ndo not agree on the start of an FPDU\"), the correct framing-error\nclass for this inconsistency."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"683f7cfbf514193d63c0efa079f3352bde84c2e0","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"4a331582011d9e8089af8aa2a61ec6b4443bb245","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"33a8b5e971e294ec2a7b74211c545e09efd8e9ac","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"14553be882d9ce91749c9d64041de66e34ad8e70","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"1012896f4225e8f801ff3c1648023845b66dfb11","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"775b4dc9618a99a1fa48b57554041a5dc17e1336","versionType":"git"},{"version":"8b6a361b8c482f22ac99c3273285ff16b23fba91","status":"affected","lessThan":"0ce1bc9e46ecabe84772bb561e373c0d9876d6f2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/infiniband/sw/siw/siw_qp_rx.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.3","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/infiniband/sw/siw/siw_qp_rx.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/683f7cfbf514193d63c0efa079f3352bde84c2e0"},{"url":"https://git.kernel.org/stable/c/4a331582011d9e8089af8aa2a61ec6b4443bb245"},{"url":"https://git.kernel.org/stable/c/33a8b5e971e294ec2a7b74211c545e09efd8e9ac"},{"url":"https://git.kernel.org/stable/c/14553be882d9ce91749c9d64041de66e34ad8e70"},{"url":"https://git.kernel.org/stable/c/c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2"},{"url":"https://git.kernel.org/stable/c/1012896f4225e8f801ff3c1648023845b66dfb11"},{"url":"https://git.kernel.org/stable/c/775b4dc9618a99a1fa48b57554041a5dc17e1336"},{"url":"https://git.kernel.org/stable/c/0ce1bc9e46ecabe84772bb561e373c0d9876d6f2"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - A remote attacker triggers this by sending a malformed iWARP FPDU over an established TCP connection; the kernel processes it in the TCP softirq receive path via siw_tcp_rx_data without any local access.\nAC:L - The attacker fully controls the peer-supplied mpa_len field and can reliably underflow fpdu_part_rem with a single crafted packet (e.g., mpa_len=0 on a tagged WRITE with hdr_len=16); no races or uncontrollable memory layout are required.\nPR:N - Exploitation requires only network reachability to a host running an iWARP listener (e.g., SMB Direct/RDMA-over-TCP on siw); completing the MPA/TCP handshake does not require any local account or elevated privileges on the victim system.\nUI:N - No victim user interaction is needed; the malformed FPDU is processed automatically when received on the connected TCP socket during normal kernel softirq handling.\nS:U - Impact is confined to kernel memory and RDMA-registered buffers on the victim host; this is standard in-kernel memory corruption without crossing a VM, container, or IOMMU security boundary.\nC:H - The negative copy length is promoted to a huge unsigned value in skb_copy_bits, producing a multi-gigabyte out-of-bounds read; KASAN confirmed use-after-free with a 4294967295-byte read, enabling arbitrary kernel memory disclosure.\nI:H - The same corrupted length drives skb_copy_bits writes into RDMA target memory (siw_rx_kva/siw_rx_umem) after siw_check_mem is bypassed by negative len, enabling out-of-bounds writes exploitable for memory corruption and potential code execution.\nA:H - KASAN reports use-after-free in skb_copy_bits during normal receive processing, and this class of kernel memory corruption reliably causes oops/panic or exploitable instability under attacker control."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:39:14.704Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"5.10.258"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"5.15.209"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"6.6.142"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"6.12.92"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64102","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:36:18.801204Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-190","lang":"en","type":"CWE","description":"CWE-190 Integer Overflow or Wraparound"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:28:11.907Z"}}]}}}