{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64102", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.033Z", "datePublished": "2026-07-19T15:40:06.776Z", "dateUpdated": "2026-08-05T12:39:14.704Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:39:14.704Z" }, "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." } ], "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/infiniband/sw/siw/siw_qp_rx.c" ], "versions": [ { "version": "8b6a361b8c482f22ac99c3273285ff16b23fba91", "lessThan": "683f7cfbf514193d63c0efa079f3352bde84c2e0", "status": "affected", "versionType": "git" }, { "version": "8b6a361b8c482f22ac99c3273285ff16b23fba91", "lessThan": "4a331582011d9e8089af8aa2a61ec6b4443bb245", "status": "affected", "versionType": "git" }, { "version": "8b6a361b8c482f22ac99c3273285ff16b23fba91", "lessThan": "33a8b5e971e294ec2a7b74211c545e09efd8e9ac", "status": "affected", "versionType": "git" }, { "version": "8b6a361b8c482f22ac99c3273285ff16b23fba91", "lessThan": "14553be882d9ce91749c9d64041de66e34ad8e70", "status": "affected", "versionType": "git" }, { "version": "8b6a361b8c482f22ac99c3273285ff16b23fba91", "lessThan": "c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2", "status": "affected", "versionType": "git" }, { "version": "8b6a361b8c482f22ac99c3273285ff16b23fba91", "lessThan": "1012896f4225e8f801ff3c1648023845b66dfb11", "status": "affected", "versionType": "git" }, { "version": "8b6a361b8c482f22ac99c3273285ff16b23fba91", "lessThan": "775b4dc9618a99a1fa48b57554041a5dc17e1336", "status": "affected", "versionType": "git" }, { "version": "8b6a361b8c482f22ac99c3273285ff16b23fba91", "lessThan": "0ce1bc9e46ecabe84772bb561e373c0d9876d6f2", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/infiniband/sw/siw/siw_qp_rx.c" ], "versions": [ { "version": "5.3", "status": "affected" }, { "version": "0", "lessThan": "5.3", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.258", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.209", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.175", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.142", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.92", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.34", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.11", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "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" } ] } ] } ], "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" } ], "title": "RDMA/siw: Reject MPA FPDU length underflow before signed receive math", "x_generator": { "engine": "bippy-1.2.0" } } } }