CVE-2023-53222: jfs: jfs_dmap: Validate db_l2nbperpage while mounting

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-15 · updated 2026-08-04
Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: jfs: jfs_dmap: Validate db_l2nbperpage while mounting In jfs_dmap.c at line 381, BLKTODMAP is used to get a logical block number inside dbFree(). db_l2nbperpage, which is the log2 number of blocks per page, is passed as an argument to BLKTODMAP which uses it for shifting. Syzbot reported a shift out-of-bounds crash because db_l2nbperpage is too big. This happens because the large value is set without any validation in dbMount() at line 181. Thus, make sure that db_l2nbperpage is correct while mounting. Max number of blocks per page = Page size / Min block size => log2(Max num_block per page) = log2(Page size / Min block size) = log2(Page size) - log2(Min block size) => Max db_l2nbperpage = L2PSIZE - L2MINBLOCKSIZE

Affected products

Linux kernel: before 4.14.322; from 4.15 before 4.19.291; from 4.20 before 5.4.251; from 5.5 before 5.10.188; from 5.11 before 5.15.121; from 5.16 before 6.1.40 — fixed in 4.14.322, 4.19.291, 5.10.188, 5.15.121, 5.4.251, 6.1.40

How to fix

Upgrade to a fixed version: Linux kernel 4.14.322, 4.19.291, 5.10.188, 5.15.121. Check the vendor advisory for mitigations.

References

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