CVE-2026-98237: net: wwan: mhi_wwan_mbim: guard against a cyclic NDP chain

CVE-2026-98237: net: wwan: mhi_wwan_mbim: guard against a cyclic NDP chain

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

net: wwan: mhi_wwan_mbim: guard against a cyclic NDP chain

The NDP traversal in mhi_mbim_rx() only stops when wNextNdpIndex is
zero.  Nothing requires the offsets to advance, so a modem that
points an NDP at itself, or at an earlier NDP, keeps the loop
spinning forever on one CPU.

Break out when the next NDP offset is not larger than the current
one.


Verified in a QEMU guest with a fault injector feeding the driver's
receive callback an NTB whose single NDP points at itself: the
unpatched driver spins in mhi_mbim_rx() with one CPU pinned at 100%
and the thread never returns.  With this check the loop terminates
within one iteration.

Changes in v2: move the non-increasing check to the wNextNdpIndex
retrieval site, as suggested by Loic Poulain, instead of tracking
the previous offset in a separate variable.

The Linux kernel CVE team has assigned CVE-2026-98237 to this issue.


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

	Issue introduced in 5.15 with commit aa730a9905b7b079ef2fffdab7f15dbb842f5c7c and fixed in 5.15.222 with commit 3ed36ee1b29b028f6bc2ebe100152f61a33df05a
	Issue introduced in 5.15 with commit aa730a9905b7b079ef2fffdab7f15dbb842f5c7c and fixed in 6.1.189 with commit e4b2c7b50d4f4aa1ddfff731b136d65f65b2b526
	Issue introduced in 5.15 with commit aa730a9905b7b079ef2fffdab7f15dbb842f5c7c and fixed in 6.6.158 with commit 19b5e8dd884a530d04482e1a8e547f43cad17ed7
	Issue introduced in 5.15 with commit aa730a9905b7b079ef2fffdab7f15dbb842f5c7c and fixed in 6.12.112 with commit 24ade82d6d993274e99c2c6998848751c35292e7
	Issue introduced in 5.15 with commit aa730a9905b7b079ef2fffdab7f15dbb842f5c7c and fixed in 6.18.54 with commit 8dad70ff7e25cbcfbcb5101fdbf36d98003eb653
	Issue introduced in 5.15 with commit aa730a9905b7b079ef2fffdab7f15dbb842f5c7c and fixed in 7.2.8 with commit 829fec45122da58d77a55a3b7ca514dafab98e77
	Issue introduced in 5.15 with commit aa730a9905b7b079ef2fffdab7f15dbb842f5c7c and fixed in 7.3-rc4 with commit 5d063822ac5184939c1ed377a339a01d8ae814e8

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-2026-98237
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/net/wwan/mhi_wwan_mbim.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/3ed36ee1b29b028f6bc2ebe100152f61a33df05a
	https://git.kernel.org/stable/c/e4b2c7b50d4f4aa1ddfff731b136d65f65b2b526
	https://git.kernel.org/stable/c/19b5e8dd884a530d04482e1a8e547f43cad17ed7
	https://git.kernel.org/stable/c/24ade82d6d993274e99c2c6998848751c35292e7
	https://git.kernel.org/stable/c/8dad70ff7e25cbcfbcb5101fdbf36d98003eb653
	https://git.kernel.org/stable/c/829fec45122da58d77a55a3b7ca514dafab98e77
	https://git.kernel.org/stable/c/5d063822ac5184939c1ed377a339a01d8ae814e8