From: Claire Chang tientzu@chromium.org
[ Upstream commit 94e2bd0b259ed39a755fdded47e6734acf1ce464 ]
If a device is getting removed or reprobed during resume, use-after-free might happen. For example, h5_btrtl_resume() schedules a work queue for device reprobing, which of course requires removal first.
If the removal happens in parallel with the device_resume() and wins the race to acquire device_lock(), removal may remove the device from the PM lists and all, but device_resume() is already running and will continue when the lock can be acquired, thus calling rfkill_resume().
During this, if rfkill_set_block() is then called after the corresponding *_unregister() and kfree() are called, there will be an use-after-free in hci_rfkill_set_block():
BUG: KASAN: use-after-free in hci_rfkill_set_block+0x58/0xc0 [bluetooth] ... Call trace: dump_backtrace+0x0/0x154 show_stack+0x20/0x2c dump_stack+0xbc/0x12c print_address_description+0x88/0x4b0 __kasan_report+0x144/0x168 kasan_report+0x10/0x18 check_memory_region+0x19c/0x1ac __kasan_check_write+0x18/0x24 hci_rfkill_set_block+0x58/0xc0 [bluetooth] rfkill_set_block+0x9c/0x120 rfkill_resume+0x34/0x70 dpm_run_callback+0xf0/0x1f4 device_resume+0x210/0x22c
Fix this by checking rfkill->registered in rfkill_resume(). device_del() in rfkill_unregister() requires device_lock() and the whole rfkill_resume() is also protected by the same lock via device_resume(), we can make sure either the rfkill->registered is false before rfkill_resume() starts or the rfkill device won't be unregistered before rfkill_resume() returns.
As async_resume() holds a reference to the device, at this level there can be no use-after-free; only in the user that doesn't expect this scenario.
Fixes: 8589086f4efd ("Bluetooth: hci_h5: Turn off RTL8723BS on suspend, reprobe on resume") Signed-off-by: Claire Chang tientzu@chromium.org Link: https://lore.kernel.org/r/20201110084908.219088-1-tientzu@chromium.org [edit commit message for clarity and add more info provided later] Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/rfkill/core.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/net/rfkill/core.c b/net/rfkill/core.c index 6c089320ae4f1..5bba7c36ac74f 100644 --- a/net/rfkill/core.c +++ b/net/rfkill/core.c @@ -876,6 +876,9 @@ static int rfkill_resume(struct device *dev)
rfkill->suspended = false;
+ if (!rfkill->registered) + return 0; + if (!rfkill->persistent) { cur = !!(rfkill->state & RFKILL_BLOCK_SW); rfkill_set_block(rfkill, cur);