In the Linux kernel, the following vulnerability has been resolved:

sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl

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.

Affected Software

References

• https://git.kernel.org/stable/c/0769449b0a5eabc3545337217ae690e46673e73a
• https://git.kernel.org/stable/c/325ea49fc43cbc03a5e1e37de8f0ca6357ced4b1
• https://git.kernel.org/stable/c/4a46b2f5dce02539e88a300800812bd24a45e097
• https://git.kernel.org/stable/c/6c8ad7e8cf29eb55836e7a0215f967746ab2b504
• https://git.kernel.org/stable/c/77393806c76b6b44f1c44bd957788c8bd9152c45
• https://git.kernel.org/stable/c/91ba94d3f7afca195b224f77a72044fbde1389ce
• https://git.kernel.org/stable/c/adf098e2a8a1e1fc075d6a5ba2edd13cf7189082
• https://git.kernel.org/stable/c/cdcd80292106df5cda325426e96495503e41f947