DEBIAN-CVE-2023-52478

In the Linux kernel, the following vulnerability has been resolved: HID: logitech-hidpp: Fix kernel crash on receiver USB disconnect hidppconnectevent() has four time-of-check vs time-of-use (TOCTOU) races when it races with itself. hidppconnectevent() primarily runs from a workqueue but it also runs on probe() and if a "device-connected" packet is received by the hw when the thread running hidppconnectevent() from probe() is waiting on the hw, then a second thread running hidppconnectevent() will be started from the workqueue. This opens the following races (note the below code is simplified): 1. Retrieving + printing the protocol (harmless race): if (!hidpp->protocolmajor) { hidpprootgetprotocolversion() hidpp->protocolmajor = response.rap.params[0]; } We can actually see this race hit in the dmesg in the abrt output attached to rhbz#2227968: [ 3064.624215] logitech-hidpp-device 0003:046D:4071.0049: HID++ 4.5 device connected. [ 3064.658184] logitech-hidpp-device 0003:046D:4071.0049: HID++ 4.5 device connected. Testing with extra logging added has shown that after this the 2 threads take turn grabbing the hw access mutex (sendmutex) so they ping-pong through all the other TOCTOU cases managing to hit all of them: 2. Updating the name to the HIDPP name (harmless race): if (hidpp->name == hdev->name) { ... hidpp->name = newname; } 3. Initializing the powersupply class for the battery (problematic!): hidppinitializebattery() { if (hidpp->battery.ps) return 0; probebattery(); /* Blocks, threads take turns executing this */ hidpp->battery.desc.properties = devmkmemdup(dev, hidppbatteryprops, cnt, GFPKERNEL); hidpp->battery.ps = devmpowersupplyregister(&hidpp->hiddev->dev, &hidpp->battery.desc, cfg); } 4. Creating delayed inputdevice (potentially problematic): if (hidpp->delayedinput) return; hidpp->delayedinput = hidppallocateinput(hdev); The really big problem here is 3. Hitting the race leads to the following sequence: hidpp->battery.desc.properties = devmkmemdup(dev, hidppbatteryprops, cnt, GFPKERNEL); hidpp->battery.ps = devmpowersupplyregister(&hidpp->hiddev->dev, &hidpp->battery.desc, cfg); ... hidpp->battery.desc.properties = devmkmemdup(dev, hidppbatteryprops, cnt, GFPKERNEL); hidpp->battery.ps = devmpowersupplyregister(&hidpp->hiddev->dev, &hidpp->battery.desc, cfg); So now we have registered 2 power supplies for the same battery, which looks a bit weird from userspace's pov but this is not even the really big problem. Notice how: 1. This is all devm-maganaged 2. The hidpp->battery.desc struct is shared between the 2 power supplies 3. hidpp->battery.desc.properties points to the result from the second devmkmemdup() This causes a use after free scenario on USB disconnect of the receiver: 1. The last registered power supply class device gets unregistered 2. The memory from the last devmkmemdup() call gets freed, hidpp->battery.desc.properties now points to freed memory 3. The first registered power supply class device gets unregistered, this involves sending a remove uevent to userspace which invokes powersupplyuevent() to fill the uevent data 4. powersupplyuevent() uses hidpp->battery.desc.properties which now points to freed memory leading to backtraces like this one: Sep 22 20:01:35 eric kernel: BUG: unable to handle page fault for address: ffffb2140e017f08 ... Sep 22 20:01:35 eric kernel: Workqueue: usbhubwq hubevent Sep 22 20:01:35 eric kernel: RIP: 0010:powersupplyuevent+0xee/0x1d0 ... Sep 22 20:01:35 eric kernel: ? asmexcpagefault+0x26/0x30 Sep 22 20:01:35 eric kernel: ? powersupplyuevent+0xee/0x1d0 Sep 22 20:01:35 eric kernel: ? powersupplyuevent+0x10d/0x1d0 Sep 22 20:01:35 eric kernel: devuevent+0x10f/0x2d0 Sep 22 20:01:35 eric kernel: kobjectueventenv+0x291/0x680 Sep 22 20:01:35 eric kernel: ---truncated---