CVE-2026-74679: usb: gadget: f_ncm: Use unsigned int for ndp_index

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

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

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

usb: gadget: f_ncm: Use unsigned int for ndp_index

The variable ndp_index is declared as a signed integer, but it stores
the return value of get_ncm(), which is unsigned.

A malicious host can supply a large offset that overflows the signed
ndp_index, making it negative. Because ndp_index is compared against
unsigned bounds, this negative value bypasses sanity checks and leads
to an out-of-bounds read when calculating the address of the NDP
block (ntb_ptr + ndp_index).

Fix this by changing ndp_index to unsigned int to ensure consistent
unsigned comparisons throughout the function.

The Linux kernel CVE team has assigned CVE-2026-74679 to this issue.


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

	Issue introduced in 3.17 with commit 370af734dfaf8336b496b386e194648e097e248a and fixed in 5.10.265 with commit 9c8c6825a750fcd3efbe922847ca70ccd5a66857
	Issue introduced in 3.17 with commit 370af734dfaf8336b496b386e194648e097e248a and fixed in 5.15.216 with commit a1c0deeba4a46481543d6b09c665f758c54c3a1a
	Issue introduced in 3.17 with commit 370af734dfaf8336b496b386e194648e097e248a and fixed in 6.1.183 with commit d13f650a3485b58c124b3cda45597e8002c9c833
	Issue introduced in 3.17 with commit 370af734dfaf8336b496b386e194648e097e248a and fixed in 6.6.152 with commit 11413d7ed42174b8f5d8d0b6a25d10dc88239b21
	Issue introduced in 3.17 with commit 370af734dfaf8336b496b386e194648e097e248a and fixed in 6.12.104 with commit 5b2b3a3229a3f4c493ffdee53aee2f173b6f13b3
	Issue introduced in 3.17 with commit 370af734dfaf8336b496b386e194648e097e248a and fixed in 6.18.45 with commit d328fdc607fa1bb668ad512e1c918a120f78f337
	Issue introduced in 3.17 with commit 370af734dfaf8336b496b386e194648e097e248a and fixed in 7.1.9 with commit fc9e54e22845c4da29588ca0986cb7c795b5a262
	Issue introduced in 3.17 with commit 370af734dfaf8336b496b386e194648e097e248a and fixed in 7.2 with commit 6b1c8a9403a26cb0fed7a648916c74dc236da591

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-2026-74679
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/usb/gadget/function/f_ncm.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/9c8c6825a750fcd3efbe922847ca70ccd5a66857
	https://git.kernel.org/stable/c/a1c0deeba4a46481543d6b09c665f758c54c3a1a
	https://git.kernel.org/stable/c/d13f650a3485b58c124b3cda45597e8002c9c833
	https://git.kernel.org/stable/c/11413d7ed42174b8f5d8d0b6a25d10dc88239b21
	https://git.kernel.org/stable/c/5b2b3a3229a3f4c493ffdee53aee2f173b6f13b3
	https://git.kernel.org/stable/c/d328fdc607fa1bb668ad512e1c918a120f78f337
	https://git.kernel.org/stable/c/fc9e54e22845c4da29588ca0986cb7c795b5a262
	https://git.kernel.org/stable/c/6b1c8a9403a26cb0fed7a648916c74dc236da591