CVE-2021-47004

Summary

CVE-2021-47004 is a vulnerability affecting the Linux kernel that has been addressed. In the context of CP disabling mode, two issues were identified when using Large File System (LFS) or Synchronous Single Write (SSR) mode to select victims. Firstly, in LFS mode, the victim should not have any checkpointed data after Garbage Collection (GC), but the check for valid checkpoint blocks in the current segment rather than the section was found to be insufficient. Secondly, with SSR or AT-SSR modes, the target segment for writes can potentially contain both checkpointed and newly written blocks, and selecting such a segment can lead to panic or data corruption during allocation. This can occur when the target segment has a fewer number of valid checkpoint blocks than 512, GC migrates valid blocks to another segment, and GC selects the target segment via the allocator, despite having no free space.

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