Subject: CVE-2024-35825: usb: gadget: ncm: Fix handling of zero block length packets

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

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

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

usb: gadget: ncm: Fix handling of zero block length packets

While connecting to a Linux host with CDC_NCM_NTB_DEF_SIZE_TX
set to 65536, it has been observed that we receive short packets,
which come at interval of 5-10 seconds sometimes and have block
length zero but still contain 1-2 valid datagrams present.

According to the NCM spec:

"If wBlockLength = 0x0000, the block is terminated by a
short packet. In this case, the USB transfer must still
be shorter than dwNtbInMaxSize or dwNtbOutMaxSize. If
exactly dwNtbInMaxSize or dwNtbOutMaxSize bytes are sent,
and the size is a multiple of wMaxPacketSize for the
given pipe, then no ZLP shall be sent.

wBlockLength= 0x0000 must be used with extreme care, because
of the possibility that the host and device may get out of
sync, and because of test issues.

wBlockLength = 0x0000 allows the sender to reduce latency by
starting to send a very large NTB, and then shortening it when
the sender discovers that there’s not sufficient data to justify
sending a large NTB"

However, there is a potential issue with the current implementation,
as it checks for the occurrence of multiple NTBs in a single
giveback by verifying if the leftover bytes to be processed is zero
or not. If the block length reads zero, we would process the same
NTB infintely because the leftover bytes is never zero and it leads
to a crash. Fix this by bailing out if block length reads zero.

The Linux kernel CVE team has assigned CVE-2024-35825 to this issue.

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

	Issue introduced in 4.19.297 with commit ff3ba016263e and fixed in 4.19.312 with commit e2dbfea520e6
	Issue introduced in 5.4.259 with commit e7ca00f35d8a and fixed in 5.4.274 with commit a766761d206e
	Issue introduced in 5.10.199 with commit 17c653d4913b and fixed in 5.10.215 with commit ef846cdbd100
	Issue introduced in 5.15.136 with commit 7014807fb7ef and fixed in 5.15.154 with commit 92b051b87658
	Issue introduced in 6.1.59 with commit 49fbc18378ae and fixed in 6.1.84 with commit 7664ee8bd803
	Issue introduced in 6.6 with commit 427694cfaafa and fixed in 6.6.24 with commit a0f77b5d6067
	Issue introduced in 6.6 with commit 427694cfaafa and fixed in 6.7.12 with commit 6b2c73111a25
	Issue introduced in 6.6 with commit 427694cfaafa and fixed in 6.8 with commit f90ce1e04cbc
	Issue introduced in 4.14.328 with commit 5bdf93a2f545
	Issue introduced in 6.5.8 with commit 4bf1a9d20c65

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-2024-35825
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/e2dbfea520e60d58e0c498ba41bde10452257779
	https://git.kernel.org/stable/c/a766761d206e7c36d7526e0ae749949d17ca582c
	https://git.kernel.org/stable/c/ef846cdbd100f7f9dc045e8bcd7fe4b3a3713c03
	https://git.kernel.org/stable/c/92b051b87658df7649ffcdef522593f21a2b296b
	https://git.kernel.org/stable/c/7664ee8bd80309b90d53488b619764f0a057f2b7
	https://git.kernel.org/stable/c/a0f77b5d6067285b8eca0ee3bd1e448a6258026f
	https://git.kernel.org/stable/c/6b2c73111a252263807b7598682663dc33aa4b4c
	https://git.kernel.org/stable/c/f90ce1e04cbcc76639d6cba0fdbd820cd80b3c70