Skip to content
CVE PROGRAM SOURCE RECORD9.8 Critical

CVE-2026-64102

RDMA/siw: Reject MPA FPDU length underflow before signed receive math

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
Linux

Description

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 8b6a361b8c482f22ac99c3273285ff16b23fba91 to < 683f7cfbf514193d63c0efa079f3352bde84c2e0affected
  • 8b6a361b8c482f22ac99c3273285ff16b23fba91 to < 4a331582011d9e8089af8aa2a61ec6b4443bb245affected
  • 8b6a361b8c482f22ac99c3273285ff16b23fba91 to < 33a8b5e971e294ec2a7b74211c545e09efd8e9acaffected
  • 8b6a361b8c482f22ac99c3273285ff16b23fba91 to < 14553be882d9ce91749c9d64041de66e34ad8e70affected
  • 8b6a361b8c482f22ac99c3273285ff16b23fba91 to < c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2affected
  • 8b6a361b8c482f22ac99c3273285ff16b23fba91 to < 1012896f4225e8f801ff3c1648023845b66dfb11affected
  • 8b6a361b8c482f22ac99c3273285ff16b23fba91 to < 775b4dc9618a99a1fa48b57554041a5dc17e1336affected
  • 8b6a361b8c482f22ac99c3273285ff16b23fba91 to < 0ce1bc9e46ecabe84772bb561e373c0d9876d6f2affected

Linux Linux

Default version status: affected

  • 5.3affected
  • 0 to < 5.3unaffected
  • 5.10.258 to ≤ 5.10.*unaffected
  • 5.15.209 to ≤ 5.15.*unaffected
  • 6.1.175 to ≤ 6.1.*unaffected
  • 6.6.142 to ≤ 6.6.*unaffected
  • 6.12.92 to ≤ 6.12.*unaffected
  • 6.18.34 to ≤ 6.18.*unaffected
  • 7.0.11 to ≤ 7.0.*unaffected
  • 7.1 to ≤ *unaffected

References