CVE-2024-57923 is a vulnerability identified in the Linux kernel's Btrfs filesystem compression code, specifically affecting the zlib compression path on IBM s390 architecture hardware acceleration. The issue arises from incorrect handling of the input data length parameter (strm.avail_in) passed to the zlib_compress_folios() function. The vulnerability occurs because the code sets strm.avail_in to a multiple of PAGE_SIZE regardless of the actual input data length, which can cause the number of bytes read to exceed the legitimate input range. This leads to an assertion failure in the btrfs_compress_folios() function, triggering a kernel BUG and causing a kernel panic. The problem is particularly evident on s390 hardware with zlib hardware acceleration enabled, as demonstrated by the kernel panic logs and call traces provided. The assertion failure indicates a logic error in the compression routine, which can cause system instability or crashes when Btrfs compression is used on affected systems. Although no known exploits are reported in the wild, the vulnerability can be triggered by specially crafted input data to the compression function, potentially leading to denial of service (DoS) through kernel panic. The vulnerability is fixed by correcting the calculation of strm.avail_in to ensure it does not exceed the actual input length, preventing out-of-bounds reads and assertion failures.

For European organizations running Linux systems with Btrfs filesystems on IBM s390 hardware or emulated environments, this vulnerability poses a risk of system crashes and denial of service. The kernel panic triggered by this bug can lead to unplanned downtime, data unavailability, and potential disruption of critical services. Organizations relying on Btrfs compression for storage efficiency may experience instability if the vulnerability is exploited or triggered inadvertently. Although the vulnerability does not appear to allow privilege escalation or remote code execution, the impact on availability can be significant, especially for enterprise environments using s390 mainframes or z/VM virtualization platforms common in financial, governmental, and large-scale data center operations. The lack of known exploits reduces immediate risk, but the potential for DoS and system instability necessitates prompt patching to maintain operational continuity and data integrity.

1. Apply the official Linux kernel patches that fix the strm.avail_in calculation in the Btrfs compression code for s390 hardware acceleration as soon as they become available. 2. For organizations using s390 hardware, consider temporarily disabling Btrfs compression or switching to alternative filesystems until patches are applied. 3. Monitor kernel logs for assertion failures or kernel panics related to btrfs_compress_folios to detect potential exploitation attempts or accidental triggers. 4. Implement robust backup and recovery procedures to mitigate data loss risks from unexpected system crashes. 5. Test kernel updates in staging environments that replicate production s390 configurations to ensure stability before deployment. 6. Coordinate with hardware and Linux distribution vendors to receive timely updates and advisories specific to s390 platforms. 7. Limit access to systems running vulnerable kernels to trusted administrators to reduce the risk of malicious triggering of the vulnerability.