CVE-2026-64574: wifi: mac80211: tear down new links on vif update error path

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

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

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

wifi: mac80211: tear down new links on vif update error path

When ieee80211_vif_update_links() adds new links it allocates a link
container for each and calls ieee80211_link_init() (which registers the
per-link debugfs files with file->private_data pointing into the container)
and ieee80211_link_setup(). If the subsequent drv_change_vif_links() fails,
the error path restores the old pointers and jumps to 'free', which frees
the new containers but never removes their debugfs entries or stops the
links. The debugfs files survive with file->private_data dangling at the
freed container, so a later open()+read() (e.g. link-1/txpower)
dereferences freed memory in ieee80211_if_read_link(), a use-after-free.

The removal path already dismantles links correctly via
ieee80211_tear_down_links(), which removes each link's keys and debugfs
entries and calls ieee80211_link_stop(); the add path on the error branch
does not. Commit be1ba9ed221f ("wifi: mac80211: avoid weird state in error
path") hardened this same error path for the link-removal case
(new_links == 0) but left the newly-added links' teardown unaddressed.

drv_change_vif_links() can fail at runtime on MLO drivers (internal
allocation / queue / firmware command failures).

Remove the new links' debugfs entries and stop them before freeing.

  BUG: KASAN: slab-use-after-free in ieee80211_if_read_link (net/mac80211/debugfs_netdev.c:127)
  Read of size 8 at addr ffff888011290000 by task exploit/145
  Call Trace:
   ...
   ieee80211_if_read_link (net/mac80211/debugfs_netdev.c:127)
   short_proxy_read (fs/debugfs/file.c:373)
   vfs_read (fs/read_write.c:572)
   ksys_read (fs/read_write.c:716)
   do_syscall_64 (arch/x86/entry/syscall_64.c:94)
   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
  ...
  Oops: general protection fault, probably for non-canonical address 0xdffffc000000000a
  RIP: 0010:ieee80211_if_read_link (net/mac80211/debugfs_netdev.c:127)
  Kernel panic - not syncing: Fatal exception

The Linux kernel CVE team has assigned CVE-2026-64574 to this issue.


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

	Issue introduced in 6.4 with commit 170cd6a66d9a164180eb4dc72d50afa6ce1ce566 and fixed in 6.6.148 with commit 329589417214d3b7221432e5b266ed2bba7ff674
	Issue introduced in 6.4 with commit 170cd6a66d9a164180eb4dc72d50afa6ce1ce566 and fixed in 6.12.101 with commit c57d97f381306bbfba174e8f708419e007824e0c
	Issue introduced in 6.4 with commit 170cd6a66d9a164180eb4dc72d50afa6ce1ce566 and fixed in 6.18.42 with commit 0f7eaeb950adb77f71beb546e5ab30f90b41fe6f
	Issue introduced in 6.4 with commit 170cd6a66d9a164180eb4dc72d50afa6ce1ce566 and fixed in 7.1.6 with commit 901a73523e093beff123b54b1ceaf3113f18acc9
	Issue introduced in 6.4 with commit 170cd6a66d9a164180eb4dc72d50afa6ce1ce566 and fixed in 7.2-rc5 with commit 952c02b33f56207a160421bcd61e7ac53c9c59ae

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-2026-64574
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:
	net/mac80211/link.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/329589417214d3b7221432e5b266ed2bba7ff674
	https://git.kernel.org/stable/c/c57d97f381306bbfba174e8f708419e007824e0c
	https://git.kernel.org/stable/c/0f7eaeb950adb77f71beb546e5ab30f90b41fe6f
	https://git.kernel.org/stable/c/901a73523e093beff123b54b1ceaf3113f18acc9
	https://git.kernel.org/stable/c/952c02b33f56207a160421bcd61e7ac53c9c59ae