CVE-2023-54321

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

driver core: fix potential null-ptr-deref in device_add()

I got the following null-ptr-deref report while doing fault injection test:

BUG: kernel NULL pointer dereference, address: 0000000000000058 CPU: 2 PID: 278 Comm: 37-i2c-ds2482 Tainted: G B W N 6.1.0-rc3+ RIP: 0010:klistput+0x2d/0xd0 Call Trace: <TASK> klistremove+0xf1/0x1c0 devicereleasedriverinternal+0x196/0x210 busremovedevice+0x1bd/0x240 deviceadd+0xd3d/0x1100 w1addmasterdevice+0x476/0x490 [wire] ds2482probe+0x303/0x3e0 [ds2482]

This is how it happened:

w1allocdev() // The dev->driver is set to w1masterdriver. memcpy(&dev->dev, device, sizeof(struct device)); deviceadd() busadddevice() dpmsysfsadd() // It fails, calls busremove_device.

// error path
bus_remove_device()
  // The dev->driver is not null, but driver is not bound.
  __device_release_driver()
    klist_remove(&dev->p->knode_driver) <-- It causes null-ptr-deref.

// normal path
bus_probe_device() // It's not called yet.
  device_bind_driver()

If dev->driver is set, in the error path after calling busadddevice() in deviceadd(), busremovedevice() is called, then the device will be detached from driver. But devicebinddriver() is not called yet, so it causes null-ptr-deref while access the 'knodedriver'. To fix this, set dev->driver to null in the error path before calling busremovedevice().