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CVE-2021-47549

Disclosure Date: May 24, 2024 •
CVE-2021-47549
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

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.

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CVSS V3 Severity and Metrics
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General Information

Offensive Application
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Utility Class
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Ports
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OS
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Vulnerable Versions
Linux cdcd80292106
Linux not down converted
Prerequisites
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Discovered By
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Metasploit Module
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Vendors

  • Linux

Products

  • Linux
Technical Analysis