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

From: libaokun (A)
Date: Sun Nov 21 2021 - 21:50:38 EST


在 2021/11/22 10:33, Damien Le Moal 写道:
On 2021/11/22 11:03, libaokun (A) wrote:
在 2021/11/20 20:01, Sergei Shtylyov 写道:
Hello!

On 20.11.2021 6:34, Baokun Li wrote:

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
  s/commands/functions/?
OK! I'm going to modify this in V3.


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.
  You mean AHCI? I don't see where you reference ahci (or achi)...
Yes, it's AHCI, I'm sorry for a spelling error here..

ahci_platform_ops in drivers/ata/libahci_platform.c


Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
  Doesn't this need to go into the stable trees?

I felt it was needed because the bug was triggered in a very simple way,

although PPC linux is rare these days.

And I will add

Fixes: faf0b2e5afe7 ("drivers/ata: add support to Freescale 3.0Gbps SATA Controller").
Also add:

Cc: stable@xxxxxxxxxxxxxxx


---
  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,
  Why not just add it to the initializer for sata_fsl_ops?

This is the AHCI of the reference.

Most ATA drivers add host_stop to to the  initializer for  xxx_platform_ops,

such as ahci_platform_ops, ahci_brcm_platform_ops, and ahci_imx_ops.

It feels like this separates the port operation from the host operation,

making the hierarchy of the code clearer.


[...]

MBR, Sergei
.

Thank you very much for your advice.

If there's nothing else to modify, I'll send a patch V3.

--
With Best Regards,
Baokun Li
.



Thank you very much for your advice.

I'm about to send a patch V3 with the changes suggested by you.

--
With Best Regards,
Baokun Li
.