CVE-2026-45999

Summary

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

erofs: fix unsigned underflow in z_erofs_lz4_handle_overlap()

Some crafted images can have illegal (!partial_decoding && m_llen < m_plen) extents, and the LZ4 inplace decompression path can be wrongly hit, but it cannot handle (outpages < inpages) properly: "outpages - inpages" wraps to a large value and the subsequent rq->out[] access reads past the decompressed_pages array.

However, such crafted cases can correctly result in a corruption report in the normal LZ4 non-inplace path.

Let's add an additional check to fix this for backporting.

Reproducible image (base64-encoded gzipped blob):

H4sIAJGR12kCA+3SPUoDQRgG4MkmkkZk8QRbRFIIi9hbpEjrHQI5ghfwCN5BLCzTGtLbBI+g dilSJo1CnIm7GEXFxhT6PDDwfrs73/ywIQD/1ePD4r7Ou6ETsrq4mu7XcWfj++Pb58nJU/9i PNtbjhan04/9GtX4qVYc814WDqt6FaX5s+ZwXXeq52lndT6IuVvlblytLMvh4Gzwaf90nsvz 2DF/21+20T/ldgp5s1jXRaN4t/8izsy/OUB6e/Qa79r+JwAAAAAAAL52vQVuGQAAAP6+my1w ywAAAAAAAADwu14ATsEYtgBQAAA=

$ mount -t erofs -o cache_strategy=disabled foo.erofs /mnt $ dd if=/mnt/data of=/dev/null bs=4096 count=1

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/778acd52e9497806fbd2cea7f770c41d6850fc48
• https://git.kernel.org/stable/c/118ff71ff09ebaf323a09af9e911517321a299f4
• https://git.kernel.org/stable/c/43a878639b90e9721ffa5eb616a7e6d8454adef3
• https://git.kernel.org/stable/c/f1374fa6e57fd836623668d782ded9244cfd2938
• https://git.kernel.org/stable/c/c9ce18e6bb2c467ec85756dc7989b547b7584fee
• https://git.kernel.org/stable/c/bbbbb3f0d7864238a8da2a94cd6ec013fee06a2e
• https://git.kernel.org/stable/c/21e161de2dc660b1bb70ef5b156ab8e6e1cca3ab

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