CVE-2023-53777

Summary

In the Linux kernel, the following vulnerability has been resolved:

erofs: kill hooked chains to avoid loops on deduplicated compressed images

After heavily stressing EROFS with several images which include a hand-crafted image of repeated patterns for more than 46 days, I found two chains could be linked with each other almost simultaneously and form a loop so that the entire loop won't be submitted. As a consequence, the corresponding file pages will remain locked forever.

It can be only observed on data-deduplicated compressed images. For example, consider two chains with five pclusters in total: Chain 1: 2->3->4->5 – The tail pcluster is 5; Chain 2: 5->1->2 – The tail pcluster is 2.

Chain 2 could link to Chain 1 with pcluster 5; and Chain 1 could link to Chain 2 at the same time with pcluster 2.

Since hooked chains are all linked locklessly now, I have no idea how to simply avoid the race. Instead, let's avoid hooked chains completely until I could work out a proper way to fix this and end users finally tell us that it's needed to add it back.

Actually, this optimization can be found with multi-threaded workloads (especially even more often on deduplicated compressed images), yet I'm not sure about the overall system impacts of not having this compared with implementation complexity.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/d3b39ea24835ac03da1a30f93ae7c05d55a40191
• https://git.kernel.org/stable/c/b5b0d52f00e4bacb0ebdf47cd7016b0485fffad2
• https://git.kernel.org/stable/c/10c2b98a40d9044a3e97f4697ca6213bad7e19c2
• https://git.kernel.org/stable/c/967c28b23f6c89bb8eef6a046ea88afe0d7c1029

• ←Previous
• Next→