Patch "driver core: fix potential null-ptr-deref in device_add()" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     driver-core-fix-potential-null-ptr-deref-in-device_a.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ffaa283979798a1966b4ef1cb01a8280eefc22cf
Author: Yang Yingliang <yangyingliang@xxxxxxxxxx>
Date:   Mon Dec 5 11:49:04 2022 +0800

    driver core: fix potential null-ptr-deref in device_add()
    
    [ Upstream commit f6837f34a34973ef6600c08195ed300e24e97317 ]
    
    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:
     <TASK>
     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().
    
    Fixes: 57eee3d23e88 ("Driver core: Call device_pm_add() after bus_add_device() in device_add()")
    Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20221205034904.2077765-1-yangyingliang@xxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index d02501933467d..e5c15061070b7 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -3551,6 +3551,7 @@ int device_add(struct device *dev)
 	device_pm_remove(dev);
 	dpm_sysfs_remove(dev);
  DPMError:
+	dev->driver = NULL;
 	bus_remove_device(dev);
  BusError:
 	device_remove_attrs(dev);