btrfs: insert tree mod log move in push_node_left

published 2025-10-04 13 mo ago modified 2026-10-03 37 d ago also EUVD-2025-32354

cvss: 5.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits: 0; none known

In the Linux kernel, the following vulnerability has been resolved:

There is a fairly unlikely race condition in tree mod log rewind that can result in a kernel panic which has the following trace:

[530.569] BTRFS critical (device sda3): unable to find logical 0 length 4096 [530.585] BTRFS critical (device sda3): unable to find logical 0 length 4096 [530.602] BUG: kernel NULL pointer dereference, address: 0000000000000002 [530.618] #PF: supervisor read access in kernel mode [530.629] #PF: error_code(0x0000) - not-present page [530.641] PGD 0 P4D 0 [530.647] Oops: 0000 [#1] SMP [530.654] CPU: 30 PID: 398973 Comm: below Kdump: loaded Tainted: G S O K 5.12.0-0_fbk13_clang_7455_gb24de3bdb045 #1 [530.680] Hardware name: Quanta Mono Lake-M.2 SATA 1HY9U9Z001G/Mono Lake-M.2 SATA, BIOS F20_3A15 08/16/2017 [530.703] RIP: 0010:__btrfs_map_block+0xaa/0xd00 [530.755] RSP: 0018:ffffc9002c2f7600 EFLAGS: 00010246 [530.767] RAX: ffffffffffffffea RBX: ffff888292e41000 RCX: f2702d8b8be15100 [530.784] RDX: ffff88885fda6fb8 RSI: ffff88885fd973c8 RDI: ffff88885fd973c8 [530.800] RBP: ffff888292e410d0 R08: ffffffff82fd7fd0 R09: 00000000fffeffff [530.816] R10: ffffffff82e57fd0 R11: ffffffff82e57d70 R12: 0000000000000000 [530.832] R13: 0000000000001000 R14: 0000000000001000 R15: ffffc9002c2f76f0 [530.848] FS: 00007f38d64af000(0000) GS:ffff88885fd80000(0000) knlGS:0000000000000000 [530.866] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [530.880] CR2: 0000000000000002 CR3: 00000002b6770004 CR4: 00000000003706e0 [530.896] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [530.912] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [530.928] Call Trace: [530.934] ? btrfs_printk+0x13b/0x18c [530.943] ? btrfs_bio_counter_inc_blocked+0x3d/0x130 [530.955] btrfs_map_bio+0x75/0x330 [530.963] ? kmem_cache_alloc+0x12a/0x2d0 [530.973] ? btrfs_submit_metadata_bio+0x63/0x100 [530.984] btrfs_submit_metadata_bio+0xa4/0x100 [530.995] submit_extent_page+0x30f/0x360 [531.004] read_extent_buffer_pages+0x49e/0x6d0 [531.015] ? submit_extent_page+0x360/0x360 [531.025] btree_read_extent_buffer_pages+0x5f/0x150 [531.037] read_tree_block+0x37/0x60 [531.046] read_block_for_search+0x18b/0x410 [531.056] btrfs_search_old_slot+0x198/0x2f0 [531.066] resolve_indirect_ref+0xfe/0x6f0 [531.076] ? ulist_alloc+0x31/0x60 [531.084] ? kmem_cache_alloc_trace+0x12e/0x2b0 [531.095] find_parent_nodes+0x720/0x1830 [531.105] ? ulist_alloc+0x10/0x60 [531.113] iterate_extent_inodes+0xea/0x370 [531.123] ? btrfs_previous_extent_item+0x8f/0x110 [531.134] ? btrfs_search_path_in_tree+0x240/0x240 [531.146] iterate_inodes_from_logical+0x98/0xd0 [531.157] ? btrfs_search_path_in_tree+0x240/0x240 [531.168] btrfs_ioctl_logical_to_ino+0xd9/0x180 [531.179] btrfs_ioctl+0xe2/0x2eb0

This occurs when logical inode resolution takes a tree mod log sequence number, and then while backref walking hits a rewind on a busy node which has the following sequence of tree mod log operations (numbers filled in from a specific example, but they are somewhat arbitrary)

REMOVE_WHILE_FREEING slot 532 REMOVE_WHILE_FREEING slot 531 REMOVE_WHILE_FREEING slot 530 ... REMOVE_WHILE_FREEING slot 0 REMOVE slot 455 REMOVE slot 454 REMOVE slot 453 ... REMOVE slot 0 ADD slot 455 ADD slot 454 ADD slot 453 ... ADD slot 0 MOVE src slot 0 -> dst slot 456 nritems 533 REMOVE slot 455 REMOVE slot 454 REMOVE slot 453 ... REMOVE slot 0

When this sequence gets applied via btrfs_tree_mod_log_rewind, it allocates a fresh rewind eb, and first inserts the correct key info for the 533 elements, then overwrites the first 456 of them, then decrements the count by 456 via the add ops, then rewinds the move by doing a memmove from 456:988->0:532. We have never written anything past 532, ---truncated---

Patch / fix

fixed in 1 distros 2 links 3

Linux Linux 6.1.189, 6.4.4, 6.5

debian suse

linux Debian 12 6.1.190-1
linux Debian 14, Debian 13 6.4.4-1

debian advisories DEBIAN-CVE-2023-53538

kernel-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
kernel-syms-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
kernel-rt_debug Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
kernel-source-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1
kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1
kernel-rt Real Time Module 15 SP7 6.4.0-150700.7.22.1
kernel-syms-rt Real Time Module 15 SP7 6.4.0-150700.7.22.1

suse advisories SUSE-SU-2025:4301-1 SUSE-SU-2025:21052-1 SUSE-SU-2025:21064-1 SUSE-SU-2025:4141-1 SUSE-SU-2025:4140-1 SUSE-SU-2025:4132-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-53538 updated 2026-11-07 cvss 5.5

kernel: btrfs: insert tree mod log move in push_node_left

Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
affected: no fix planned “Out of support scope”
Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
affected: no fix available “Fix deferred”
Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-476 NULL Pointer Dereference

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2023-53538
NVD CVE-2023-53538

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary