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:klist_put+0x2d/0xd0 Call Trace: klist_remove+0xf1/0x1c0 device_release_driver_internal+0x196/0x210 bus_remove_device+0x1bd/0x240 device_add+0xd3d/0x1100 w1_add_master_device+0x476/0x490 [wire] ds2482_probe+0x303/0x3e0 [ds2482]
This is how it happened:
w1_alloc_dev() // The dev->driver is set to w1_master_driver. memcpy(&dev->dev, device, sizeof(struct device)); device_add() bus_add_device() dpm_sysfs_add() // It fails, calls bus_remove_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 bus_add_device() in device_add(), bus_remove_device() is called, then the device will be detached from driver. But device_bind_driver() is not called yet, so it causes null-ptr-deref while access the 'knode_driver'. To fix this, set dev->driver to null in the error path before calling bus_remove_device().