# CVE-2026-23018: linux: In the Linux kernel, the following vulnerability has been resolved: btrfs: release path before initializing extent t... CVE-2026-23018 is fixed in 14 products on 1 platform, first by DEBIAN-CVE-2026-23018, released January 31, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-23018 - Priority: Routine - CVSS: 5.5 (medium) - EPSS: 0.0012 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Jan 31, 2026 ## Description In the Linux kernel, the following vulnerability has been resolved: btrfs: release path before initializing extent tree in btrfs_read_locked_inode() In btrfs_read_locked_inode() we are calling btrfs_init_file_extent_tree() while holding a path with a read locked leaf from a subvolume tree, and btrfs_init_file_extent_tree() may do a GFP_KERNEL allocation, which can trigger reclaim. This can create a circular lock dependency which lockdep warns about with the following splat: [6.1433] ====================================================== [6.1574] WARNING: possible circular locking dependency detected [6.1583] 6.18.0+ #4 Tainted: G U [6.1591] ------------------------------------------------------ [6.1599] kswapd0/117 is trying to acquire lock: [6.1606] ffff8d9b6333c5b8 (&delayed_node->mutex){+.+.}-{3:3}, at: __btrfs_release_delayed_node.part.0+0x39/0x2f0 [6.1625] but task is already holding lock: [6.1633] ffffffffa4ab8ce0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x195/0xc60 [6.1646] which lock already depends on the new lock. [6.1657] the existing dependency chain (in reverse order) is: [6.1667] -> #2 (fs_reclaim){+.+.}-{0:0}: [6.1677] fs_reclaim_acquire+0x9d/0xd0 [6.1685] __kmalloc_cache_noprof+0x59/0x750 [6.1694] btrfs_init_file_extent_tree+0x90/0x100 [6.1702] btrfs_read_locked_inode+0xc3/0x6b0 [6.1710] btrfs_iget+0xbb/0xf0 [6.1716] btrfs_lookup_dentry+0x3c5/0x8e0 [6.1724] btrfs_lookup+0x12/0x30 [6.1731] lookup_open.isra.0+0x1aa/0x6a0 [6.1739] path_openat+0x5f7/0xc60 [6.1746] do_filp_open+0xd6/0x180 [6.1753] do_sys_openat2+0x8b/0xe0 [6.1760] __x64_sys_openat+0x54/0xa0 [6.1768] do_syscall_64+0x97/0x3e0 [6.1776] entry_SYSCALL_64_after_hwframe+0x76/0x7e [6.1784] -> #1 (btrfs-tree-00){++++}-{3:3}: [6.1794] lock_release+0x127/0x2a0 [6.1801] up_read+0x1b/0x30 [6.1808] btrfs_search_slot+0x8e0/0xff0 [6.1817] btrfs_lookup_inode+0x52/0xd0 [6.1825] __btrfs_update_delayed_inode+0x73/0x520 [6.1833] btrfs_commit_inode_delayed_inode+0x11a/0x120 [6.1842] btrfs_log_inode+0x608/0x1aa0 [6.1849] btrfs_log_inode_parent+0x249/0xf80 [6.1857] btrfs_log_dentry_safe+0x3e/0x60 [6.1865] btrfs_sync_file+0x431/0x690 [6.1872] do_fsync+0x39/0x80 [6.1879] __x64_sys_fsync+0x13/0x20 [6.1887] do_syscall_64+0x97/0x3e0 [6.1894] entry_SYSCALL_64_after_hwframe+0x76/0x7e [6.1903] -> #0 (&delayed_node->mutex){+.+.}-{3:3}: [6.1913] __lock_acquire+0x15e9/0x2820 [6.1920] lock_acquire+0xc9/0x2d0 [6.1927] __mutex_lock+0xcc/0x10a0 [6.1934] __btrfs_release_delayed_node.part.0+0x39/0x2f0 [6.1944] btrfs_evict_inode+0x20b/0x4b0 [6.1952] evict+0x15a/0x2f0 [6.1958] prune_icache_sb+0x91/0xd0 [6.1966] super_cache_scan+0x150/0x1d0 [6.1974] do_shrink_slab+0x155/0x6f0 [6.1981] shrink_slab+0x48e/0x890 [6.1988] shrink_one+0x11a/0x1f0 [6.1995] shrink_node+0xbfd/0x1320 [6.1002] balance_pgdat+0x67f/0xc60 [6.1321] kswapd+0x1dc/0x3e0 [6.1643] kthread+0xff/0x240 [6.1965] ret_from_fork+0x223/0x280 [6.1287] ret_from_fork_asm+0x1a/0x30 [6.1616] other info that might help us debug this: [6.1561] Chain exists of: &delayed_node->mutex --> btrfs-tree-00 --> fs_reclaim [6.1503] Possible unsafe locking scenario: [6.1110] CPU0 CPU1 [6.1411] ---- ---- [6.1707] lock(fs_reclaim); [6.1998] lock(btrfs-tree-00); [6.1291] lock(fs_reclaim); [6.1581] lock(&del ---truncated--- ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | dtb-aarch64 opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-64kb opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-64kb sles 16.0 | 6.12.0-160000.27.1 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | kernel-azure opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-azure sles 16.0 | 6.12.0-160000.27.1 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | kernel-default opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-default sles 16.0 | 6.12.0-160000.27.1 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | kernel-default-base opensuse-leap 16.0 | 6.12.0-160000.27.1.160000.2.8 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-default-base sles 16.0 | 6.12.0-160000.27.1.160000.2.8 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | kernel-docs opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-docs sles 16.0 | 6.12.0-160000.27.1 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | kernel-kvmsmall opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-kvmsmall sles 16.0 | 6.12.0-160000.27.1 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | kernel-obs-build opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-obs-qa opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-obs-qa sles 16.0 | 6.12.0-160000.27.1 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | kernel-rt opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-source opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-source sles 16.0 | 6.12.0-160000.27.1 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | kernel-syms opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-syms sles 16.0 | 6.12.0-160000.27.1 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | kernel-zfcpdump opensuse-leap 16.0 | 6.12.0-160000.27.1 | [OPENSUSE-SU-2026:20416-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20416-1.md) | Mar 25, 2026 | | Linux | kernel-zfcpdump sles 16.0 | 6.12.0-160000.27.1 | [SUSE-SU-2026:20931-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20931-1.md) | Mar 25, 2026 | | Linux | linux Debian 14 | 6.18.8-1 | [DEBIAN-CVE-2026-23018](https://patchblox.com/security/data/fix/linux/debian-cve-2026-23018.md) | Jan 31, 2026 | --- Data as of 2026-11-08T19:12:23Z UTC. 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