CVE-2026-64102 (GCVE-0-2026-64102)
Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-10-19 20:28
VLAI
EPSS
VEX
Title
RDMA/siw: Reject MPA FPDU length underflow before signed receive math
Summary
In the Linux kernel, the following vulnerability has been resolved:
RDMA/siw: Reject MPA FPDU length underflow before signed receive math
A malicious connected siw peer can send an iWARP FPDU whose MPA length
field (c_hdr->mpa_len, 16 bit big-endian, peer-controlled) is smaller
than the fixed DDP/RDMAP header for the announced opcode. Soft-iWARP
parses the full header in siw_get_hdr() based on iwarp_pktinfo[opcode]
.hdr_len, but never compares mpa_len against that header length.
siw_tcp_rx_data() then derives
srx->fpdu_part_rem = be16_to_cpu(mpa_len) - fpdu_part_rcvd
+ MPA_HDR_SIZE;
where fpdu_part_rcvd equals iwarp_pktinfo[opcode].hdr_len at this
point. For a tagged WRITE (hdr_len 16, MPA_HDR_SIZE 2) the smallest
on-wire mpa_len of 0 yields fpdu_part_rem = -14, and any mpa_len below
hdr_len - MPA_HDR_SIZE underflows to a negative int.
The signed value then flows into siw_proc_write()/siw_proc_rresp() as
bytes = min(srx->fpdu_part_rem, srx->skb_new);
is handed to siw_check_mem() as an int len (whose interval check
addr + len > mem->va + mem->len is satisfied for a valid base when
len is negative), and reaches siw_rx_data() -> siw_rx_kva() /
siw_rx_umem() -> skb_copy_bits() as a signed copy length. The header
copy branch in skb_copy_bits() promotes that to size_t, producing a
multi-gigabyte read.
KASAN under a KUnit harness that drives the real kernel TCP receive
path -- a loopback AF_INET socketpair, the malformed FPDU written via
kernel_sendmsg, sk_data_ready firing in softirq, tcp_read_sock
dispatching to siw_tcp_rx_data -- reports:
BUG: KASAN: use-after-free in skb_copy_bits+0x284/0x480
Read of size 4294967295 at addr ffff888...
Call Trace:
skb_copy_bits
siw_rx_kva
siw_rx_data
siw_check_mem
siw_proc_write
siw_tcp_rx_data
__tcp_read_sock
siw_qp_llp_data_ready
tcp_data_ready
tcp_data_queue
Add the missing invariant at the earliest point where the peer header
is fully assembled. iwarp_pktinfo[*].hdr_len - MPA_HDR_SIZE is exactly
the value the siw transmitter uses as the minimum mpa_len for each
opcode (drivers/infiniband/sw/siw/siw_qp.c:33), so this matches the
protocol contract. Out-of-range FPDUs terminate the connection with
TERM_ERROR_LAYER_LLP / LLP_ETYPE_MPA / LLP_ECODE_FPDU_START -- which
is RFC 5044 Section 8 error code 3 ("Marker and ULPDU Length fields
do not agree on the start of an FPDU"), the correct framing-error
class for this inconsistency.
Severity
9.8 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 15:36 UTC
CWE
- CWE-190 - Integer Overflow or Wraparound
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
8b6a361b8c482f22ac99c3273285ff16b23fba91 , < 683f7cfbf514193d63c0efa079f3352bde84c2e0
(git)
Affected: 8b6a361b8c482f22ac99c3273285ff16b23fba91 , < 4a331582011d9e8089af8aa2a61ec6b4443bb245 (git) Affected: 8b6a361b8c482f22ac99c3273285ff16b23fba91 , < 33a8b5e971e294ec2a7b74211c545e09efd8e9ac (git) Affected: 8b6a361b8c482f22ac99c3273285ff16b23fba91 , < 14553be882d9ce91749c9d64041de66e34ad8e70 (git) Affected: 8b6a361b8c482f22ac99c3273285ff16b23fba91 , < c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2 (git) Affected: 8b6a361b8c482f22ac99c3273285ff16b23fba91 , < 1012896f4225e8f801ff3c1648023845b66dfb11 (git) Affected: 8b6a361b8c482f22ac99c3273285ff16b23fba91 , < 775b4dc9618a99a1fa48b57554041a5dc17e1336 (git) Affected: 8b6a361b8c482f22ac99c3273285ff16b23fba91 , < 0ce1bc9e46ecabe84772bb561e373c0d9876d6f2 (git) |
guessed | |
| Linux | Linux |
Affected:
5.3
Unaffected: 0 , < 5.3 (semver) Unaffected: 5.10.258 , ≤ 5.10.* (semver) Unaffected: 5.15.209 , ≤ 5.15.* (semver) Unaffected: 6.1.175 , ≤ 6.1.* (semver) Unaffected: 6.6.142 , ≤ 6.6.* (semver) Unaffected: 6.12.92 , ≤ 6.12.* (semver) Unaffected: 6.18.34 , ≤ 6.18.* (semver) Unaffected: 7.0.11 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix) |
guessed |
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"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-\u003empa_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-\u003efpdu_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-\u003efpdu_part_rem, srx-\u003eskb_new);\n\nis handed to siw_check_mem() as an int len (whose interval check\naddr + len \u003e mem-\u003eva + mem-\u003elen is satisfied for a valid base when\nlen is negative), and reaches siw_rx_data() -\u003e siw_rx_kva() /\nsiw_rx_umem() -\u003e 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."
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"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-\u003empa_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-\u003efpdu_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-\u003efpdu_part_rem, srx-\u003eskb_new);\n\nis handed to siw_check_mem() as an int len (whose interval check\naddr + len \u003e mem-\u003eva + mem-\u003elen is satisfied for a valid base when\nlen is negative), and reaches siw_rx_data() -\u003e siw_rx_kva() /\nsiw_rx_umem() -\u003e 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."
}
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"title": "kernel: RDMA/siw: Reject MPA FPDU length underflow before signed receive math",
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"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-\u003empa_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-\u003efpdu_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-\u003efpdu_part_rem, srx-\u003eskb_new);\n\nis handed to siw_check_mem() as an int len (whose interval check\naddr + len \u003e mem-\u003eva + mem-\u003elen is satisfied for a valid base when\nlen is negative), and reaches siw_rx_data() -\u003e siw_rx_kva() /\nsiw_rx_umem() -\u003e 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."
}
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"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."
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.