cbcvebase.
CVE-2026-64102
published 2026-07-19

CVE-2026-64102: In the Linux kernel, the following vulnerability has been resolved: RDMA/siw: Reject MPA FPDU length underflow before signed receive math A malicious connected…

PriorityP350critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.50%
41.1th percentile
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 transmit

Affected

66 ranges· showing 25
VendorProductVersion rangeFixed in
linuxlinux——
linuxlinux>= 8b6a361b8c482f22ac99c3273285ff16b23fba91 < 683f7cfbf514193d63c0efa079f3352bde84c2e0683f7cfbf514193d63c0efa079f3352bde84c2e0
linuxlinux>= 8b6a361b8c482f22ac99c3273285ff16b23fba91 < 4a331582011d9e8089af8aa2a61ec6b4443bb2454a331582011d9e8089af8aa2a61ec6b4443bb245
linuxlinux>= 8b6a361b8c482f22ac99c3273285ff16b23fba91 < 33a8b5e971e294ec2a7b74211c545e09efd8e9ac33a8b5e971e294ec2a7b74211c545e09efd8e9ac
linuxlinux>= 8b6a361b8c482f22ac99c3273285ff16b23fba91 < 14553be882d9ce91749c9d64041de66e34ad8e7014553be882d9ce91749c9d64041de66e34ad8e70
linuxlinux>= 8b6a361b8c482f22ac99c3273285ff16b23fba91 < c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2
linuxlinux>= 8b6a361b8c482f22ac99c3273285ff16b23fba91 < 1012896f4225e8f801ff3c1648023845b66dfb111012896f4225e8f801ff3c1648023845b66dfb11
linuxlinux>= 8b6a361b8c482f22ac99c3273285ff16b23fba91 < 775b4dc9618a99a1fa48b57554041a5dc17e1336775b4dc9618a99a1fa48b57554041a5dc17e1336
linuxlinux>= 8b6a361b8c482f22ac99c3273285ff16b23fba91 < 0ce1bc9e46ecabe84772bb561e373c0d9876d6f20ce1bc9e46ecabe84772bb561e373c0d9876d6f2
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel——
linuxlinux_kernel>= 5.11 < 5.15.2095.15.209
linuxlinux_kernel>= 5.16 < 6.1.1756.1.175
linuxlinux_kernel>= 5.3 < 5.10.2585.10.258
linuxlinux_kernel>= 6.13 < 6.18.346.18.34
linuxlinux_kernel>= 6.19 < 7.0.117.0.11
linuxlinux_kernel>= 6.2 < 6.6.1426.6.142
linuxlinux_kernel>= 6.7 < 6.12.926.12.92
ubuntulinux——
ubuntulinux-aws——
ubuntulinux-aws-5.15——
ubuntulinux-aws-6.8——

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vendor_redhat9.8CRITICAL
vendor_ubuntu9.1CRITICAL
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