Bluetooth: btmtksdio: fix infinite loop in btmtksdio_txrx_work()
3Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackepss 0.2%
exploitation probability
0.2%top 93% of all CVEs
observed exploitation
nono source reports it
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.
Affected products
Linux · LinuxReferences
https://git.kernel.org/stable/c/0039bdde36b23ccf1196635f1d52c5490481544dhttps://git.kernel.org/stable/c/0f0a83e26a9c7fd4b243c315ce07161d2496d83dhttps://git.kernel.org/stable/c/466540e045d01fcacf383a5beb8a2dad2fc53a26https://git.kernel.org/stable/c/7b429d611060e87752e848851815537963726493https://git.kernel.org/stable/c/a257407e2bbbb099ed427719a50563f67fa366d8https://git.kernel.org/stable/c/f6682c23b6fac4780d297ae4662053d17e58fd52