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

scsi: ufs: core: Fix use-after free in init error and remove paths

devm_blk_crypto_profile_init() registers a cleanup handler to run when
the associated (platform-) device is being released. For UFS, the
crypto private data and pointers are stored as part of the ufs_hba's
data structure 'struct ufs_hba::crypto_profile'. This structure is
allocated as part of the underlying ufshcd and therefore Scsi_host
allocation.

During driver release or during error handling in ufshcd_pltfrm_init(),
this structure is released as part of ufshcd_dealloc_host() before the
(platform-) device associated with the crypto call above is released.
Once this device is released, the crypto cleanup code will run, using
the just-released 'struct ufs_hba::crypto_profile'. This causes a
use-after-free situation:

  Call trace:
   kfree+0x60/0x2d8 (P)
   kvfree+0x44/0x60
   blk_crypto_profile_destroy_callback+0x28/0x70
   devm_action_release+0x1c/0x30
   release_nodes+0x6c/0x108
   devres_release_all+0x98/0x100
   device_unbind_cleanup+0x20/0x70
   really_probe+0x218/0x2d0

In other words, the initialisation code flow is:

  platform-device probe
    ufshcd_pltfrm_init()
      ufshcd_alloc_host()
        scsi_host_alloc()
          allocation of struct ufs_hba
          creation of scsi-host devices
    devm_blk_crypto_profile_init()
      devm registration of cleanup handler using platform-device

and during error handling of ufshcd_pltfrm_init() or during driver
removal:

  ufshcd_dealloc_host()
    scsi_host_put()
      put_device(scsi-host)
        release of struct ufs_hba
  put_device(platform-device)
    crypto cleanup handler

To fix this use-after free, change ufshcd_alloc_host() to register a
devres action to automatically cleanup the underlying SCSI device on
ufshcd destruction, without requiring explicit calls to
ufshcd_dealloc_host(). This way:

    * the crypto profile and all other ufs_hba-owned resources are
      destroyed before SCSI (as they've been registered after)
    * a memleak is plugged in tc-dwc-g210-pci.c remove() as a
      side-effect
    * EXPORT_SYMBOL_GPL(ufshcd_dealloc_host) can be removed fully as
      it's not needed anymore
    * no future drivers using ufshcd_alloc_host() could ever forget
      adding the cleanup