Bug 2402192 (CVE-2022-50542)

Summary: CVE-2022-50542 kernel: media: si470x: Fix use-after-free in si470x_int_in_callback()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A use-after-free vulnerability was found in the Linux kernel si470x USB FM radio driver's error handling. A local user with privileges to connect USB devices can physically attach a malicious or malfunctioning si470x USB radio device that triggers initialization failure after USB request submission, causing the driver to free the device structure without canceling pending USB interrupts, which leads to accessing freed memory when the interrupt callback fires and results in memory corruption that can cause denial of service via kernel crash or potentially privilege escalation through heap manipulation.
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Description OSIDB Bzimport 2025-10-07 16:01:52 UTC
In the Linux kernel, the following vulnerability has been resolved:

media: si470x: Fix use-after-free in si470x_int_in_callback()

syzbot reported use-after-free in si470x_int_in_callback() [1].  This
indicates that urb->context, which contains struct si470x_device
object, is freed when si470x_int_in_callback() is called.

The cause of this issue is that si470x_int_in_callback() is called for
freed urb.

si470x_usb_driver_probe() calls si470x_start_usb(), which then calls
usb_submit_urb() and si470x_start().  If si470x_start_usb() fails,
si470x_usb_driver_probe() doesn't kill urb, but it just frees struct
si470x_device object, as depicted below:

si470x_usb_driver_probe()
  ...
  si470x_start_usb()
    ...
    usb_submit_urb()
    retval = si470x_start()
    return retval
  if (retval < 0)
    free struct si470x_device object, but don't kill urb

This patch fixes this issue by killing urb when si470x_start_usb()
fails and urb is submitted.  If si470x_start_usb() fails and urb is
not submitted, i.e. submitting usb fails, it just frees struct
si470x_device object.