CVE-2026-45984: In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix use-after-free in iomap inline data write path The inline data buffer ...

Description

In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix use-after-free in iomap inline data write path The inline data buffer head (dibh) is being released prematurely in gfs2_iomap_begin() via release_metapath() while iomap->inline_data still points to dibh->b_data. This causes a use-after-free when iomap_write_end_inline() later attempts to write to the inline data area. The bug sequence: 1. gfs2_iomap_begin() calls gfs2_meta_inode_buffer() to read inode metadata into dibh 2. Sets iomap->inline_data = dibh->b_data + sizeof(struct gfs2_dinode) 3. Calls release_metapath() which calls brelse(dibh), dropping refcount to 0 4. kswapd reclaims the page (~39ms later in the syzbot report) 5. iomap_write_end_inline() tries to memcpy() to iomap->inline_data 6. KASAN detects use-after-free write to freed memory Fix by storing dibh in iomap->private and incrementing its refcount with get_bh() in gfs2_iomap_begin(). The buffer is then properly released in gfs2_iomap_end() after the inline write completes, ensuring the page stays alive for the entire iomap operation. Note: A C reproducer is not available for this issue. The fix is based on analysis of the KASAN report and code review showing the buffer head is freed before use. [agruenba: Take buffer head reference in gfs2_iomap_begin() to avoid leaks in gfs2_iomap_get() and gfs2_iomap_alloc().]

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.13%

2.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-416

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	>= 5.2, < 5.10.252
Linux	Linux Kernel	>= 5.11, < 5.15.202
Linux	Linux Kernel	>= 5.16, < 6.1.165
Linux	Linux Kernel	>= 6.2, < 6.6.128
Linux	Linux Kernel	>= 6.7, < 6.12.75
Linux	Linux Kernel	>= 6.13, < 6.18.14
Linux	Linux Kernel	>= 6.19, < 6.19.4

References

Timeline

Published: May 27, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-45984?

In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix use-after-free in iomap inline data write path The inline data buffer head (dibh) is being released prematurely in gfs2_iomap_begin() via release_metapath() while iomap->inline_data still points to dibh->b_data. This causes a use-after-free when iomap_write_end_inline() later attempts to write to the inline data area. The bug sequence: 1. gfs2_iomap_begin() calls gfs2_meta_inode_buffer() to read inode metadata into dibh 2. Sets iomap->inline_data = dibh->b_data + sizeof(struct gfs2_dinode) 3. Calls release_metapath() which calls brelse(dibh), dropping refcount to 0 4. kswapd reclaims the page (~39ms later in the syzbot report) 5. iomap_write_end_inline() tries to memcpy() to iomap->inline_data 6. KASAN detects use-after-free write to freed memory Fix by storing dibh in iomap->private and incrementing its refcount with get_bh() in gfs2_iomap_begin(). The buffer is then properly released in gfs2_iomap_end() after the inline write completes, ensuring the page stays alive for the entire iomap operation. Note: A C reproducer is not available for this issue. The fix is based on analysis of the KASAN report and code review showing the buffer head is freed before use. [agruenba: Take buffer head reference in gfs2_iomap_begin() to avoid leaks in gfs2_iomap_get() and gfs2_iomap_alloc().]

How severe is CVE-2026-45984?

CVE-2026-45984 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.

How do I fix CVE-2026-45984?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.