CVE-2026-64409

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

Bluetooth: btmtksdio: fix infinite loop in btmtksdiotxrxwork()

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

INFO: task kworker/u17:0:189 blocked for more than 122 seconds. __cancelworktimer+0x3f4/0x460 cancelworksync+0x1c/0x2c btmtksdioflush+0x2c/0x40 hcidevopensync+0x10c4/0x2190 [..]

It all boils down to incorrect timeisbeforejiffies() usage in btmtksdiotxrxwork(). The btmtksdiotxrxwork() loop is expected to be terminated if running for longer than 5*HZ. However the timeout check is twisted: timeisbeforejiffies(oldjiffies + 5*HZ) evaluates to true when oldjiffies + 5*HZ is in the past i.e. when a timeout has occurred. Using OR with timeisbeforejiffies(txrxtimeout) 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 btmtksdiotxrxwork() loop never terminates and never releases the SDIO host.

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