UBUNTU-CVE-2023-52497
In the Linux kernel, the following vulnerability has been resolved: erofs: fix lz4 inplace decompression Currently EROFS can map another compressed buffer for inplace decompression, that was used to handle the cases that some pages of compressed data are actually not in-place I/O. However, like most simple LZ77 algorithms, LZ4 expects the compressed data is arranged at the end of the decompressed buffer and it explicitly uses memmove() to handle overlapping: __________________________________________________________ |_ direction of decompression --> ____ |_ compressed data _| Although EROFS arranges compressed data like this, it typically maps two individual virtual buffers so the relative order is uncertain. Previously, it was hardly observed since LZ4 only uses memmove() for short overlapped literals and x86/arm64 memmove implementations seem to completely cover it up and they don't have this issue. Juhyung reported that EROFS data corruption can be found on a new Intel x86 processor. After some analysis, it seems that recent x86 processors with the new FSRM feature expose this issue with "rep movsb". Let's strictly use the decompressed buffer for lz4 inplace decompression for now. Later, as an useful improvement, we could try to tie up these two buffers together in the correct order.
02 / AFFECTED SOFTWARE
Affected packages
7 explicit affected versions
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13 explicit affected versions
53 explicit affected versions
7 explicit affected versions
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10 explicit affected versions
12 explicit affected versions
12 explicit affected versions
88 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
35 explicit affected versions
37 explicit affected versions
14 explicit affected versions
38 explicit affected versions
39 explicit affected versions
9 explicit affected versions
38 explicit affected versions
11 explicit affected versions
46 explicit affected versions
8 explicit affected versions
7 explicit affected versions
20 explicit affected versions
60 explicit affected versions
4 explicit affected versions
1 explicit affected versions
1 explicit affected versions
44 explicit affected versions
10 explicit affected versions
43 explicit affected versions
54 explicit affected versions
10 explicit affected versions
8 explicit affected versions
14 explicit affected versions
89 explicit affected versions
4 explicit affected versions
78 explicit affected versions
7 explicit affected versions
1 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: erofs: fix lz4 inplace decompression Currently EROFS can map another compressed buffer for inplace decompression, that was used to handle the cases that some pages of compressed data are actually not in-place I/O. However, like most simple LZ77 algorithms, LZ4 expects the compressed data is arranged at the end of the decompressed buffer and it explicitly uses memmove() to handle overlapping: __________________________________________________________ |_ direction of decompression --> ____ |_ compressed data _| Although EROFS arranges compressed data like this, it typically maps two individual virtual buffers so the relative order is uncertain. Previously, it was hardly observed since LZ4 only uses memmove() for short overlapped literals and x86/arm64 memmove implementations seem to completely cover it up and they don't have this issue. Juhyung reported that EROFS data corruption can be found on a new Intel x86 processor. After some analysis, it seems that recent x86 processors with the new FSRM feature expose this issue with "rep movsb". Let's strictly use the decompressed buffer for lz4 inplace decompression for now. Later, as an useful improvement, we could try to tie up these two buffers together in the correct order.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/3c12466b6b7bf1e56f9b32c366a3d83d87afb4de
- https://ubuntu.com/security/CVE-2023-52497
- https://ubuntu.com/security/notices/USN-6818-1
- https://ubuntu.com/security/notices/USN-6818-2
- https://ubuntu.com/security/notices/USN-6818-3
- https://ubuntu.com/security/notices/USN-6818-4
- https://ubuntu.com/security/notices/USN-6819-1
- https://ubuntu.com/security/notices/USN-6819-2
- https://ubuntu.com/security/notices/USN-6819-3
- https://ubuntu.com/security/notices/USN-6819-4
- https://ubuntu.com/security/notices/USN-6820-1
- https://ubuntu.com/security/notices/USN-6820-2
- https://ubuntu.com/security/notices/USN-6821-1
- https://ubuntu.com/security/notices/USN-6821-2
- https://ubuntu.com/security/notices/USN-6821-3
- https://ubuntu.com/security/notices/USN-6821-4
- https://ubuntu.com/security/notices/USN-6828-1
- https://ubuntu.com/security/notices/USN-6871-1
- https://ubuntu.com/security/notices/USN-6892-1
- https://ubuntu.com/security/notices/USN-6919-1
- https://ubuntu.com/security/notices/USN-7159-1
- https://ubuntu.com/security/notices/USN-7159-2
- https://ubuntu.com/security/notices/USN-7159-3
- https://ubuntu.com/security/notices/USN-7159-4
- https://ubuntu.com/security/notices/USN-7159-5
- https://ubuntu.com/security/notices/USN-7195-1
- https://ubuntu.com/security/notices/USN-7195-2
- https://www.cve.org/CVERecord?id=CVE-2023-52497