CVE-2020-29372 in Linux
Summary
by MITRE • 11/28/2020
An issue was discovered in do_madvise in mm/madvise.c in the Linux kernel before 5.6.8. There is a race condition between coredump operations and the IORING_OP_MADVISE implementation, aka CID-bc0c4d1e176e.
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Analysis
by VulDB Data Team • 05/30/2026
The vulnerability identified as CVE-2020-29372 represents a critical race condition within the Linux kernel's memory management subsystem, specifically affecting the do_madvise function in mm/madvise.c. This flaw exists in kernel versions prior to 5.6.8 and creates a dangerous scenario where concurrent operations can lead to system instability and potential security implications. The race condition manifests between coredump operations and the IORING_OP_MADVISE implementation, creating a window where memory management decisions can be corrupted or misapplied during critical system operations.
The technical flaw stems from insufficient synchronization mechanisms within the kernel's memory advice handling code. When a process attempts to perform memory management operations through the io_uring interface while a coredump is in progress, the kernel fails to properly coordinate these competing operations. This race condition allows for memory pages to be inappropriately advised of their access patterns, potentially leading to memory corruption, data loss, or system crashes. The vulnerability specifically affects the madvise system call implementation when used in conjunction with io_uring's asynchronous I/O operations, creating a complex interaction that bypasses normal kernel protection mechanisms.
Operationally, this vulnerability can have severe consequences for systems running affected kernel versions, particularly in environments where memory-intensive applications and core dump generation occur concurrently. Attackers could potentially exploit this race condition to cause system crashes, leading to denial of service conditions, or in more sophisticated scenarios, could manipulate memory advice decisions to interfere with process memory management. The impact extends beyond simple system stability issues as the vulnerability could be leveraged to bypass certain memory protection mechanisms, making it particularly concerning for security-sensitive environments. The race condition's nature means that exploitation may be intermittent but potentially devastating when it occurs.
Mitigation strategies for CVE-2020-29372 primarily involve upgrading to Linux kernel version 5.6.8 or later, where the race condition has been addressed through improved synchronization mechanisms. System administrators should prioritize patching affected systems, particularly those running memory-intensive workloads or serving as core dump targets. Additional defensive measures include monitoring for unusual memory management patterns and implementing proper access controls to limit potential exploitation vectors. The fix implemented by the kernel developers addresses the synchronization gap between coredump operations and madvise calls through enhanced locking mechanisms, ensuring proper ordering of operations. Organizations should also consider implementing kernel hardening techniques and maintaining up-to-date security patches as part of their overall security posture to prevent similar vulnerabilities from being exploited. This vulnerability aligns with CWE-362, which describes race conditions in concurrent systems, and could potentially map to ATT&CK technique T1059 for process injection or system compromise through memory manipulation.