CVE-2026-45984

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().]

Gravité et risque d'exploitation

CVE-2026-45984 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.18 %, ce qui la place devant 7.5 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, <d87268326b277af3665237ac76a73dd9fa8e21b4, 5.2, <faddeb848305e79db89ee0479bb0e33380656321, 0, 7.0, 6.1.165, <764c3c84b5683e608f43735c803a5f415046686c, 6.12.75, <815ddd27c0c7171a99fe802fdb19098ddef8b19d, d0a22a4b03b8475b7aa3fa41243c26c291407844, <=5.10.*, <=6.6.*, <=6.19.*, <1cae1bafdf9caa9b462b19af06b1a06902e4e142, <6d76febba07c40bcf358f63216d36ea68cf1c215, <=6.18.*, 6.6.128, <87d4954b5c59735a99ea98cb208d47130f6dce7d, 5.10.252, <1403989d1b502f4a2c0d0b42ccf1c25748442eff, 6.19.4, <=*, <=5.15.*, 5.15.202, <5.2, 6.18.14) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/1403989d1b502f4a2c0d0b42ccf1c25748442eff
• https://git.kernel.org/stable/c/1cae1bafdf9caa9b462b19af06b1a06902e4e142
• https://git.kernel.org/stable/c/764c3c84b5683e608f43735c803a5f415046686c
• https://git.kernel.org/stable/c/d87268326b277af3665237ac76a73dd9fa8e21b4
• https://git.kernel.org/stable/c/87d4954b5c59735a99ea98cb208d47130f6dce7d
• https://git.kernel.org/stable/c/6d76febba07c40bcf358f63216d36ea68cf1c215
• https://git.kernel.org/stable/c/815ddd27c0c7171a99fe802fdb19098ddef8b19d
• https://git.kernel.org/stable/c/faddeb848305e79db89ee0479bb0e33380656321