CVE-2022-50778
Vulnerability Scoring
Status: Received on 24 Dec 2025, 13:16 UTC
Published on: 24 Dec 2025, 13:16 UTC
CVSS Release:
CVE-2022-50778: In the Linux kernel, the following vulnerability has been resolved: fortify: Fix __compiletime_strlen() under UBSAN_BOUNDS_LOCAL With CONFIG_FORTIFY=y and CONFIG_UBSAN_LOCAL_BOUNDS=y enabled, we observe a runtime panic while running Android's Compatibility Test Suite's (CTS) android.hardware.input.cts.tests. This is stemming from a strlen() call in hidinput_allocate(). __compiletime_strlen() is implemented in terms of __builtin_object_size(), then does an array access to check for NUL-termination. A quirk of __builtin_object_size() is that for strings whose values are runtime dependent, __builtin_object_size(str, 1 or 0) returns the maximum size of possible values when those sizes are determinable at compile time. Example: static const char *v = "FOO BAR"; static const char *y = "FOO BA"; unsigned long x (int z) { // Returns 8, which is: // max(__builtin_object_size(v, 1), __builtin_object_size(y, 1)) return __builtin_object_size(z ? v : y, 1); } So when FORTIFY_SOURCE is enabled, the current implementation of __compiletime_strlen() will try to access beyond the end of y at runtime using the size of v. Mixed with UBSAN_LOCAL_BOUNDS we get a fault. hidinput_allocate() has a local C string whose value is control flow dependent on a switch statement, so __builtin_object_size(str, 1) evaluates to the maximum string length, making all other cases fault on the last character check. hidinput_allocate() could be cleaned up to avoid runtime calls to strlen() since the local variable can only have literal values, so there's no benefit to trying to fortify the strlen call site there. Perform a __builtin_constant_p() check against index 0 earlier in the macro to filter out the control-flow-dependant case. Add a KUnit test for checking the expected behavioral characteristics of FORTIFY_SOURCE internals.
The exploitability of CVE-2022-50778 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
No exploitability data is available for CVE-2022-50778.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2022-50778, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2022-50778, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
Unknown
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