Subject: CVE-2021-47549: sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl

When the `rmmod sata_fsl.ko` command is executed in the PPC64 GNU/Linux,
a bug is reported:
 ==================================================================
 BUG: Unable to handle kernel data access on read at 0x80000800805b502c
 Oops: Kernel access of bad area, sig: 11 [#1]
 NIP [c0000000000388a4] .ioread32+0x4/0x20
 LR [80000000000c6034] .sata_fsl_port_stop+0x44/0xe0 [sata_fsl]
 Call Trace:
  .free_irq+0x1c/0x4e0 (unreliable)
  .ata_host_stop+0x74/0xd0 [libata]
  .release_nodes+0x330/0x3f0
  .device_release_driver_internal+0x178/0x2c0
  .driver_detach+0x64/0xd0
  .bus_remove_driver+0x70/0xf0
  .driver_unregister+0x38/0x80
  .platform_driver_unregister+0x14/0x30
  .fsl_sata_driver_exit+0x18/0xa20 [sata_fsl]
  .__se_sys_delete_module+0x1ec/0x2d0
  .system_call_exception+0xfc/0x1f0
  system_call_common+0xf8/0x200
 ==================================================================

The triggering of the BUG is shown in the following stack:

driver_detach
  device_release_driver_internal
    __device_release_driver
      drv->remove(dev) --> platform_drv_remove/platform_remove
        drv->remove(dev) --> sata_fsl_remove
          iounmap(host_priv->hcr_base);			<---- unmap
          kfree(host_priv);                             <---- free
      devres_release_all
        release_nodes
          dr->node.release(dev, dr->data) --> ata_host_stop
            ap->ops->port_stop(ap) --> sata_fsl_port_stop
                ioread32(hcr_base + HCONTROL)           <---- UAF
            host->ops->host_stop(host)

The iounmap(host_priv->hcr_base) and kfree(host_priv) functions should
not be executed in drv->remove. These functions should be executed in
host_stop after port_stop. Therefore, we move these functions to the
new function sata_fsl_host_stop and bind the new function to host_stop.

The Linux kernel CVE team has assigned CVE-2021-47549 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 2.6.24 with commit faf0b2e5afe7 and fixed in 4.4.294 with commit cdcd80292106
	Issue introduced in 2.6.24 with commit faf0b2e5afe7 and fixed in 4.9.292 with commit 91ba94d3f7af
	Issue introduced in 2.6.24 with commit faf0b2e5afe7 and fixed in 4.14.257 with commit 325ea49fc43c
	Issue introduced in 2.6.24 with commit faf0b2e5afe7 and fixed in 4.19.220 with commit 0769449b0a5e
	Issue introduced in 2.6.24 with commit faf0b2e5afe7 and fixed in 5.4.164 with commit 77393806c76b
	Issue introduced in 2.6.24 with commit faf0b2e5afe7 and fixed in 5.10.84 with commit 4a46b2f5dce0
	Issue introduced in 2.6.24 with commit faf0b2e5afe7 and fixed in 5.15.7 with commit adf098e2a8a1
	Issue introduced in 2.6.24 with commit faf0b2e5afe7 and fixed in 5.16 with commit 6c8ad7e8cf29

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47549
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/ata/sata_fsl.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/cdcd80292106df5cda325426e96495503e41f947
	https://git.kernel.org/stable/c/91ba94d3f7afca195b224f77a72044fbde1389ce
	https://git.kernel.org/stable/c/325ea49fc43cbc03a5e1e37de8f0ca6357ced4b1
	https://git.kernel.org/stable/c/0769449b0a5eabc3545337217ae690e46673e73a
	https://git.kernel.org/stable/c/77393806c76b6b44f1c44bd957788c8bd9152c45
	https://git.kernel.org/stable/c/4a46b2f5dce02539e88a300800812bd24a45e097
	https://git.kernel.org/stable/c/adf098e2a8a1e1fc075d6a5ba2edd13cf7189082
	https://git.kernel.org/stable/c/6c8ad7e8cf29eb55836e7a0215f967746ab2b504