sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl

commit 6c8ad7e8cf29eb55836e7a0215f967746ab2b504 upstream.

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 [AgentFabulous#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.

Fixes: faf0b2e ("drivers/ata: add support to Freescale 3.0Gbps SATA Controller")
Cc: stable@vger.kernel.org
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@gmail.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/ata/sata_fsl.c

@@ -1406,6 +1406,14 @@ static int sata_fsl_init_controller(struct ata_host *host)
 	return 0;
 }
 
+static void sata_fsl_host_stop(struct ata_host *host)
+{
+        struct sata_fsl_host_priv *host_priv = host->private_data;
+
+        iounmap(host_priv->hcr_base);
+        kfree(host_priv);
+}
+
 /*
  * scsi mid-layer and libata interface structures
  */
@@ -1438,6 +1446,8 @@ static struct ata_port_operations sata_fsl_ops = {
 	.port_start = sata_fsl_port_start,
 	.port_stop = sata_fsl_port_stop,
 
+	.host_stop      = sata_fsl_host_stop,
+
 	.pmp_attach = sata_fsl_pmp_attach,
 	.pmp_detach = sata_fsl_pmp_detach,
 };
@@ -1570,8 +1580,6 @@ static int sata_fsl_remove(struct platform_device *ofdev)
 	ata_host_detach(host);
 
 	irq_dispose_mapping(host_priv->irq);
-	iounmap(host_priv->hcr_base);
-	kfree(host_priv);
 
 	return 0;
 }