[PATCH -next V2 1/2] sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl

[Baokun Li]

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) commands should
not be executed in drv->remove. These commands should be executed in
host_stop after port_stop. Therefore, we move these commands to the
new function sata_fsl_host_stop and bind the new function to host_stop
by referring to achi.

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
---
 drivers/ata/sata_fsl.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c
index e5838b23c9e0..30759fd1c3a2 100644
--- a/drivers/ata/sata_fsl.c
+++ b/drivers/ata/sata_fsl.c
@@ -1430,12 +1430,25 @@ static struct ata_port_operations sata_fsl_ops = {
 	.pmp_detach = sata_fsl_pmp_detach,
 };
 
+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);
+}
+
+static struct ata_port_operations sata_fsl_platform_ops = {
+	.inherits       = &sata_fsl_ops,
+	.host_stop      = sata_fsl_host_stop,
+};
+
 static const struct ata_port_info sata_fsl_port_info[] = {
 	{
 	 .flags = SATA_FSL_HOST_FLAGS,
 	 .pio_mask = ATA_PIO4,
 	 .udma_mask = ATA_UDMA6,
-	 .port_ops = &sata_fsl_ops,
+	 .port_ops = &sata_fsl_platform_ops,
 	 },
 };
 
@@ -1558,8 +1571,6 @@ 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;
 }
-- 
2.31.1