CVE-2026-64217: netfs: Fix overrun check in netfs_extract_user_iter()

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

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

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

netfs: Fix overrun check in netfs_extract_user_iter()

Fix netfs_extract_user_iter() so that if iov_iter_extract_pages() overfills
pages[], then those pages don't get included in the iterator constructed at
the end of the function.  If there was an overfill, memory corruption has
already happened.

The Linux kernel CVE team has assigned CVE-2026-64217 to this issue.


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

	Issue introduced in 6.3 with commit 85dd2c8ff368b1446be9febde84afe1d7aec4261 and fixed in 6.6.142 with commit 00efe58bbdcc93272d579ca24bfc912563f4a204
	Issue introduced in 6.3 with commit 85dd2c8ff368b1446be9febde84afe1d7aec4261 and fixed in 6.12.92 with commit 96cc3beb2390ba9f9c128c5733c0ccfe450dd4f9
	Issue introduced in 6.3 with commit 85dd2c8ff368b1446be9febde84afe1d7aec4261 and fixed in 6.18.34 with commit afeb32d9bf9aaeea51d0f723a19f14afb73bd94d
	Issue introduced in 6.3 with commit 85dd2c8ff368b1446be9febde84afe1d7aec4261 and fixed in 7.0.11 with commit f48b9157f0f611fa436c360648603d5ded719b12
	Issue introduced in 6.3 with commit 85dd2c8ff368b1446be9febde84afe1d7aec4261 and fixed in 7.1 with commit 0ef37eef83fad3542ee06db2940433ae1a92b39d

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-2026-64217
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:
	fs/netfs/iterator.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/00efe58bbdcc93272d579ca24bfc912563f4a204
	https://git.kernel.org/stable/c/96cc3beb2390ba9f9c128c5733c0ccfe450dd4f9
	https://git.kernel.org/stable/c/afeb32d9bf9aaeea51d0f723a19f14afb73bd94d
	https://git.kernel.org/stable/c/f48b9157f0f611fa436c360648603d5ded719b12
	https://git.kernel.org/stable/c/0ef37eef83fad3542ee06db2940433ae1a92b39d