Use-After-Free Vulnerability in Linux Kernel’s Btrfs Component

CVE-2024-56759

Summary

This vulnerability in the Linux kernel's btrfs component arises during the Copy-On-Write (COW) operation on tree blocks. When tracing is enabled and preemption occurs, there is a risk of triggering a use-after-free condition. Specifically, while processing btrfs_cow_block(), the system may preempt the task before the tracepoint trace_btrfs_cow_block() is called, leading to the release of the extent buffer before it is accessed. This critical flaw has been addressed by relocating the tracepoint invocation to a safer point in the code, ensuring that it does not occur after the extent buffer has been freed.

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