CVE-2026-64409: Bluetooth: btmtksdio: fix infinite loop in btmtksdio_txrx_work()

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

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

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

Bluetooth: btmtksdio: fix infinite loop in btmtksdio_txrx_work()

Every once in a while we see a hung btmtksdio_flush() task:

 INFO: task kworker/u17:0:189 blocked for more than 122 seconds.
 __cancel_work_timer+0x3f4/0x460
 cancel_work_sync+0x1c/0x2c
 btmtksdio_flush+0x2c/0x40
 hci_dev_open_sync+0x10c4/0x2190
 [..]

It all boils down to incorrect time_is_before_jiffies() usage in
btmtksdio_txrx_work().  The btmtksdio_txrx_work() loop is expected
to be terminated if running for longer than 5*HZ.  However the
timeout check is twisted:  time_is_before_jiffies(old_jiffies + 5*HZ)
evaluates to true when old_jiffies + 5*HZ is in the past i.e. when a
timeout has occurred.  Using OR with time_is_before_jiffies(txrx_timeout)
means that:
- before the 5-second timeout: the condition is `int_status || false`,
  so it loops as long as there are pending interrupts.
- after the 5-second timeout: the condition becomes `int_status || true`,
  which is always true.

When the loop becomes infinite btmtksdio_txrx_work() loop never
terminates and never releases the SDIO host.

Fix loop termination condition to actually enforce a 5*HZ timeout.

The Linux kernel CVE team has assigned CVE-2026-64409 to this issue.


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

	Issue introduced in 5.17 with commit 26270bc189ea4b5a8356ec99561357fc87f00b32 and fixed in 6.1.178 with commit f6682c23b6fac4780d297ae4662053d17e58fd52
	Issue introduced in 5.17 with commit 26270bc189ea4b5a8356ec99561357fc87f00b32 and fixed in 6.6.145 with commit 466540e045d01fcacf383a5beb8a2dad2fc53a26
	Issue introduced in 5.17 with commit 26270bc189ea4b5a8356ec99561357fc87f00b32 and fixed in 6.12.96 with commit 7b429d611060e87752e848851815537963726493
	Issue introduced in 5.17 with commit 26270bc189ea4b5a8356ec99561357fc87f00b32 and fixed in 6.18.39 with commit 0039bdde36b23ccf1196635f1d52c5490481544d
	Issue introduced in 5.17 with commit 26270bc189ea4b5a8356ec99561357fc87f00b32 and fixed in 7.1.4 with commit 0f0a83e26a9c7fd4b243c315ce07161d2496d83d
	Issue introduced in 5.17 with commit 26270bc189ea4b5a8356ec99561357fc87f00b32 and fixed in 7.2-rc1 with commit a257407e2bbbb099ed427719a50563f67fa366d8

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-2026-64409
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/bluetooth/btmtksdio.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/f6682c23b6fac4780d297ae4662053d17e58fd52
	https://git.kernel.org/stable/c/466540e045d01fcacf383a5beb8a2dad2fc53a26
	https://git.kernel.org/stable/c/7b429d611060e87752e848851815537963726493
	https://git.kernel.org/stable/c/0039bdde36b23ccf1196635f1d52c5490481544d
	https://git.kernel.org/stable/c/0f0a83e26a9c7fd4b243c315ce07161d2496d83d
	https://git.kernel.org/stable/c/a257407e2bbbb099ed427719a50563f67fa366d8