CVE-2022-48987 in Linux
Summary
by MITRE • 10/21/2024
In the Linux kernel, the following vulnerability has been resolved:
media: v4l2-dv-timings.c: fix too strict blanking sanity checks
Sanity checks were added to verify the v4l2_bt_timings blanking fields in order to avoid integer overflows when userspace passes weird values.
But that assumed that userspace would correctly fill in the front porch, backporch and sync values, but sometimes all you know is the total blanking, which is then assigned to just one of these fields.
And that can fail with these checks.
So instead set a maximum for the total horizontal and vertical blanking and check that each field remains below that.
That is still sufficient to avoid integer overflows, but it also allows for more flexibility in how userspace fills in these fields.
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Analysis
by VulDB Data Team • 01/18/2026
The vulnerability identified as CVE-2022-48987 resides within the Linux kernel's video4linux2 (v4l2) subsystem, specifically in the v4l2-dv-timings.c module. This issue represents a regression in the kernel's validation logic for digital video timing parameters that are crucial for proper video signal processing and display operations. The vulnerability manifests as overly restrictive sanity checks that were implemented to prevent integer overflow conditions when userspace applications provide malformed timing parameters to the kernel's video subsystem.
The technical flaw stems from an overly aggressive approach to validating blanking fields within the v4l2_bt_timings structure, which defines timing parameters for digital video signals. Originally introduced to prevent integer overflow scenarios, these validation checks assumed that userspace applications would correctly populate all timing fields including front porch, back porch, and sync values. However, this assumption proved flawed in practical implementations where userspace applications might only know the total blanking value and assign it to a single field rather than distributing it appropriately across multiple fields. This legitimate usage pattern was incorrectly rejected by the overly strict validation logic, causing valid video timing configurations to be rejected.
The operational impact of this vulnerability extends beyond simple rejection of video timing configurations, as it affects the broader video processing capabilities of Linux systems that rely on proper v4l2 functionality. When userspace applications attempt to configure video timing parameters that conform to standard practices but trigger the overly restrictive validation, the kernel fails to properly process these valid configurations. This can result in video output failures, display malfunctions, or complete video subsystem operation disruptions in systems that depend on proper timing parameter handling. The vulnerability essentially creates a false positive in the kernel's validation logic, where legitimate video timing parameters are incorrectly classified as invalid due to the restrictive nature of the checks.
The fix implemented for CVE-2022-48987 addresses this issue by establishing maximum limits for total horizontal and vertical blanking values while allowing individual fields to remain below these thresholds. This approach maintains the essential security objective of preventing integer overflow conditions while providing the necessary flexibility for legitimate userspace applications to configure video timing parameters. The solution aligns with security best practices by preserving the core protection against overflow conditions while eliminating the false positive validation errors that were blocking valid configurations. This remediation ensures that the kernel maintains robust protection against integer overflow vulnerabilities while supporting the full range of legitimate video timing parameter configurations that userspace applications might legitimately require.
From a cybersecurity perspective, this vulnerability demonstrates the importance of balancing security validation with practical usability in kernel subsystems. The fix represents a typical case where overly restrictive security measures can inadvertently create operational issues that affect legitimate use cases. The vulnerability classification aligns with CWE-129, which addresses insufficient validation of length of inputs, and relates to ATT&CK techniques focused on system exploitation through kernel-level vulnerabilities. The resolution maintains the kernel's integrity while ensuring that legitimate video processing operations can proceed without unnecessary interference from overly restrictive validation logic. This change reflects the ongoing challenge in kernel security where defensive measures must not compromise system functionality or user experience.