CVE-2025-38710
Modified Modified - Updated After Analysis
BaseFortify

Publication date: 2025-09-04

Last updated on: 2026-06-01

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: gfs2: Validate i_depth for exhash directories A fuzzer test introduced corruption that ends up with a depth of 0 in dir_e_read(), causing an undefined shift by 32 at: index = hash >> (32 - dip->i_depth); As calculated in an open-coded way in dir_make_exhash(), the minimum depth for an exhash directory is ilog2(sdp->sd_hash_ptrs) and 0 is invalid as sdp->sd_hash_ptrs is fixed as sdp->bsize / 16 at mount time. So we can avoid the undefined behaviour by checking for depth values lower than the minimum in gfs2_dinode_in(). Values greater than the maximum are already being checked for there. Also switch the calculation in dir_make_exhash() to use ilog2() to clarify how the depth is calculated. Tested with the syzkaller repro.c and xfstests '-g quick'.
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Meta Information
Published
2025-09-04
Last Modified
2026-06-01
Generated
2026-06-16
AI Q&A
2025-09-04
EPSS Evaluated
2026-06-15
NVD
CVE-2025-38710
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
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Executive Summary

This vulnerability in the Linux kernel's gfs2 filesystem involves improper validation of the i_depth value for exhash directories. A fuzzer test caused corruption resulting in an invalid depth of 0, which leads to an undefined shift operation in the code. The minimum valid depth is calculated based on the filesystem parameters, and 0 is invalid. The vulnerability is addressed by adding checks to ensure depth values are within valid ranges, preventing undefined behavior during directory operations.

Impact Analysis

This vulnerability can cause undefined behavior in the Linux kernel when handling gfs2 exhash directories, potentially leading to filesystem corruption or crashes. Such instability could affect system reliability and data integrity on systems using the gfs2 filesystem.

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