CVE-2024-47741 is a concurrency vulnerability in the Linux kernel's Btrfs filesystem implementation, specifically related to the handling of concurrent lseek(2) system calls with SEEK_DATA or SEEK_HOLE flags on the same file descriptor by multiple threads within the same process. The issue arises due to a race condition when multiple threads simultaneously invoke lseek on the same file descriptor, leading to improper handling of the file's private data pointer. Both threads may observe the private_data pointer as NULL and independently allocate separate private structures, with the second allocation overwriting the first. This results in a memory leak of the first allocated private structure. Furthermore, both threads end up sharing the same cached state record (struct btrfs_file_private::llseek_cached_state), which is intended to be task-specific. This sharing can cause use-after-free conditions because only one thread holds a reference count, and the other thread may access freed memory. Although currently the cached state is used in a manner that validates ranges before use, the underlying flaw could lead to incorrect behavior or memory corruption in future kernel versions or under different usage patterns. The fix involves serializing access to the private_data pointer assignment by holding the inode's spinlock and associating the private structure with the allocating task to prevent cross-thread misuse and use-after-free issues. This vulnerability affects Linux kernel versions prior to the patch and is relevant to systems using the Btrfs filesystem, which is commonly deployed in various Linux distributions. No known exploits are reported in the wild as of the publication date.

For European organizations, this vulnerability poses risks primarily in environments where Btrfs is used extensively, such as enterprise servers, cloud infrastructure, and development systems running Linux. The memory leak itself could lead to gradual resource exhaustion, potentially causing denial of service (DoS) conditions on critical systems. More critically, the use-after-free scenario could be exploited to cause kernel crashes or potentially escalate privileges if combined with other vulnerabilities, undermining system integrity and availability. Organizations relying on multi-threaded applications that perform concurrent file operations on Btrfs volumes are particularly at risk. Given the Linux kernel's widespread use in European data centers, cloud providers, and embedded systems, unpatched systems may face stability issues or targeted attacks exploiting this flaw. The vulnerability does not directly expose confidential data but threatens system reliability and integrity, which can disrupt business operations and critical services.

European organizations should prioritize updating their Linux kernel to the patched version that addresses CVE-2024-47741 as soon as it becomes available from their distribution vendors. Specifically, kernel updates that include the fix for serialized access to file private data and task-specific private structures must be applied. For environments where immediate patching is not feasible, organizations should audit and limit the use of Btrfs on multi-threaded applications performing concurrent lseek operations, potentially restricting such workloads or isolating them in controlled environments. Monitoring kernel logs for unusual memory allocation patterns or crashes related to Btrfs lseek operations can help detect exploitation attempts. Additionally, organizations should review and harden their multi-threaded application designs to avoid concurrent lseek calls on the same file descriptor where possible. Employing kernel live patching solutions, if supported, can reduce downtime during remediation. Finally, maintaining robust backup and recovery procedures is essential to mitigate potential service disruptions caused by exploitation.