Re: [PATCH -next V5 1/2] sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl

[Sergei Shtylyov]

On 11/26/21 5:03 AM, 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) 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: faf0b2e5afe7 ("drivers/ata: add support to Freescale 3.0Gbps SATA Controller")
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>

Reviewed-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxx>

MBR, Sergei