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

> 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)...

> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Baokun Li <libaokun1@huawei.com>

Doesn't this need to go into the stable trees?

> ---
> 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?

[...]

MBR, Sergei

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