CVE-2026-64268: RDMA/siw: bound Read Response placement to the RREAD length

From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

RDMA/siw: bound Read Response placement to the RREAD length

In drivers/infiniband/sw/siw/siw_qp_rx.c, siw_proc_rresp() places each
inbound Read Response DDP segment at sge->laddr + wqe->processed and then
accumulates wqe->processed, but it never checks the running total against
the sink buffer length on continuation segments. siw_check_sge() resolves
and validates the sink memory only on the first fragment (the if (!*mem)
branch), and siw_rresp_check_ntoh() compares the cumulative length against
wqe->bytes only on the final segment (the !frx->more_ddp_segs guard).

A connected siw peer that answers an outstanding RREAD with Read Response
segments that keep the DDP Last flag clear, carrying more total payload
than the RREAD requested, drives wqe->processed past the validated sink
buffer; the next siw_rx_data() call writes out of bounds at
sge->laddr + wqe->processed. siw runs iWARP over ordinary routable TCP,
so the peer is the remote end of an established RDMA connection and needs
no local privilege.

Bound every segment before placement, exactly as siw_proc_send() and
siw_proc_write() already do for their tagged and untagged paths, and
terminate the connection with a base-or-bounds DDP error when the
Read Response would overrun the sink buffer.

This is the second receive-path length fix for this file. A separate
change rejects an MPA FPDU length that underflows the per-fragment
remainder in the header decode; that guard does not cover this case,
because here each individual segment length is self-consistent and only
the accumulated placement offset overruns the buffer.

The Linux kernel CVE team has assigned CVE-2026-64268 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.3 with commit 8b6a361b8c482f22ac99c3273285ff16b23fba91 and fixed in 5.10.261 with commit a31b6d18ded3cc32d9ee85a6ff0726d4274887b2
	Issue introduced in 5.3 with commit 8b6a361b8c482f22ac99c3273285ff16b23fba91 and fixed in 5.15.212 with commit 595e6537ad1a210da32cbb9a7f91aa73090915ba
	Issue introduced in 5.3 with commit 8b6a361b8c482f22ac99c3273285ff16b23fba91 and fixed in 6.1.178 with commit 3ef7e052cbd05a8b13a51a07b185a39ec93ee1cf
	Issue introduced in 5.3 with commit 8b6a361b8c482f22ac99c3273285ff16b23fba91 and fixed in 6.6.145 with commit b2e26c955f8dd7e8d3f16c858db05245ea4fa817
	Issue introduced in 5.3 with commit 8b6a361b8c482f22ac99c3273285ff16b23fba91 and fixed in 6.12.96 with commit 6bc89f34a4597f9f6d41f7a60c67a3153bfe8851
	Issue introduced in 5.3 with commit 8b6a361b8c482f22ac99c3273285ff16b23fba91 and fixed in 6.18.39 with commit 423a78ff7928c2601013f73ec6d896f5597d0df5
	Issue introduced in 5.3 with commit 8b6a361b8c482f22ac99c3273285ff16b23fba91 and fixed in 7.1.4 with commit 75c93cd3c421890f49ea93f0b978b9b7bb10e5e3
	Issue introduced in 5.3 with commit 8b6a361b8c482f22ac99c3273285ff16b23fba91 and fixed in 7.2-rc1 with commit 7d29f7e9dbd844cae4d3e559cf78324b9642fd6b

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64268
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/infiniband/sw/siw/siw_qp_rx.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/a31b6d18ded3cc32d9ee85a6ff0726d4274887b2
	https://git.kernel.org/stable/c/595e6537ad1a210da32cbb9a7f91aa73090915ba
	https://git.kernel.org/stable/c/3ef7e052cbd05a8b13a51a07b185a39ec93ee1cf
	https://git.kernel.org/stable/c/b2e26c955f8dd7e8d3f16c858db05245ea4fa817
	https://git.kernel.org/stable/c/6bc89f34a4597f9f6d41f7a60c67a3153bfe8851
	https://git.kernel.org/stable/c/423a78ff7928c2601013f73ec6d896f5597d0df5
	https://git.kernel.org/stable/c/75c93cd3c421890f49ea93f0b978b9b7bb10e5e3
	https://git.kernel.org/stable/c/7d29f7e9dbd844cae4d3e559cf78324b9642fd6b