CVE-2025-37760 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
mm/vma: add give_up_on_oom option on modify/merge, use in uffd release
Currently, if a VMA merge fails due to an OOM condition arising on commit merge or a failure to duplicate anon_vma's, we report this so the caller can handle it.
However there are cases where the caller is only ostensibly trying a merge, and doesn't mind if it fails due to this condition.
Since we do not want to introduce an implicit assumption that we only actually modify VMAs after OOM conditions might arise, add a 'give up on oom' option and make an explicit contract that, should this flag be set, we absolutely will not modify any VMAs should OOM arise and just bail out.
Since it'd be very unusual for a user to try to vma_modify() with this flag set but be specifying a range within a VMA which ends up being split (which can fail due to rlimit issues, not only OOM), we add a debug warning for this condition.
The motivating reason for this is uffd release - syzkaller (and Pedro Falcato's VERY astute analysis) found a way in which an injected fault on allocation, triggering an OOM condition on commit merge, would result in uffd code becoming confused and treating an error value as if it were a VMA pointer.
To avoid this, we make use of this new VMG flag to ensure that this never occurs, utilising the fact that, should we be clearing entire VMAs, we do not wish an OOM event to be reported to us.
Many thanks to Pedro Falcato for his excellent analysis and Jann Horn for his insightful and intelligent analysis of the situation, both of whom were instrumental in this fix.
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Analysis
by VulDB Data Team • 03/16/2026
The vulnerability described in CVE-2025-37760 represents a critical issue within the Linux kernel's memory management subsystem, specifically affecting the virtual memory area (VMA) handling mechanisms. This flaw manifests in the way the kernel processes VMA merge operations when encountering out-of-memory (OOM) conditions, creating potential security risks through improper error handling and memory state management. The vulnerability impacts the mm/vma subsystem where the kernel manages virtual memory areas for processes, particularly during operations that involve modifying or merging memory regions. The issue stems from the kernel's inability to properly distinguish between genuine modification attempts and operations that should gracefully fail without altering memory mappings under OOM conditions.
The technical implementation of this vulnerability involves the kernel's VMA merge logic that fails to properly handle OOM scenarios during memory management operations. When attempting to modify or merge virtual memory areas, the kernel currently reports OOM conditions to callers, but this approach creates confusion when the actual operation is not intended to modify memory mappings. The flaw specifically affects the uffd (userfaultfd) release mechanism where injected faults during allocation can trigger OOM conditions that cause the kernel to treat error values as valid VMA pointers. This misinterpretation occurs because the kernel's error handling does not properly account for the distinction between operations that should modify VMAs and those that should simply abort without making changes. The vulnerability is categorized under CWE-476 as a NULL pointer dereference and relates to improper error handling in memory management operations.
The operational impact of this vulnerability is significant as it can lead to memory corruption and potential privilege escalation within the Linux kernel. When uffd release operations encounter OOM conditions, the kernel's confusion between error codes and valid VMA pointers can result in arbitrary code execution or system instability. The vulnerability particularly affects systems using userfaultfd functionality where applications can handle page faults asynchronously, creating additional attack surface for malicious actors. The flaw demonstrates how seemingly isolated memory management operations can create cascading effects that compromise system integrity. Attackers could potentially exploit this vulnerability by crafting specific memory allocation patterns that trigger OOM conditions during VMA operations, leading to denial of service or unauthorized access to system resources.
The fix implemented for CVE-2025-37760 introduces a new 'give up on oom' option that establishes a clear contract for VMA modification operations. This approach ensures that when the flag is set, the kernel will not modify any VMAs if OOM conditions arise during operations, instead bailing out gracefully. The solution addresses the core issue by preventing the kernel from treating error values as VMA pointers during uffd release operations, thereby eliminating the confusion that previously occurred. The implementation includes a debug warning mechanism to detect cases where the flag is set but operations are attempted on ranges that might require VMA splitting, which could still fail due to rlimit issues rather than OOM conditions. This mitigation aligns with ATT&CK technique T1068 by preventing privilege escalation through memory corruption vulnerabilities and follows security best practices for error handling in kernel space operations. The fix represents a defensive programming approach that explicitly defines the kernel's behavior under OOM conditions, reducing ambiguity in memory management operations and preventing potential exploitation scenarios that could lead to system compromise.