Security assessments indicate that CVE-2024-42103 presents a notable risk, potentially requiring prompt mitigation.
Status: Analyzed
Last updated: 🕓 26 Sep 2025, 16:09 UTC
Originally published on: 🕗 30 Jul 2024, 08:15 UTC
Time between publication and last update: 423 days
CVSS Release: version 3
nvd@nist.gov
Primary
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVE-2024-42103: In the Linux kernel, the following vulnerability has been resolved: btrfs: fix adding block group to a reclaim list and the unused list during reclaim There is a potential parallel list adding for retrying in btrfs_reclaim_bgs_work and adding to the unused list. Since the block group is removed from the reclaim list and it is on a relocation work, it can be added into the unused list in parallel. When that happens, adding it to the reclaim list will corrupt the list head and trigger list corruption like below. Fix it by taking fs_info->unused_bgs_lock. [177.504][T2585409] BTRFS error (device nullb1): error relocating ch= unk 2415919104 [177.514][T2585409] list_del corruption. next->prev should be ff1100= 0344b119c0, but was ff11000377e87c70. (next=3Dff110002390cd9c0) [177.529][T2585409] ------------[ cut here ]------------ [177.537][T2585409] kernel BUG at lib/list_debug.c:65! [177.545][T2585409] Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI [177.555][T2585409] CPU: 9 PID: 2585409 Comm: kworker/u128:2 Tainted: G W 6.10.0-rc5-kts #1 [177.568][T2585409] Hardware name: Supermicro SYS-520P-WTR/X12SPW-TF, BIOS 1.2 02/14/2022 [177.579][T2585409] Workqueue: events_unbound btrfs_reclaim_bgs_work[btrfs] [177.589][T2585409] RIP: 0010:__list_del_entry_valid_or_report.cold+0x70/0x72 [177.624][T2585409] RSP: 0018:ff11000377e87a70 EFLAGS: 00010286 [177.633][T2585409] RAX: 000000000000006d RBX: ff11000344b119c0 RCX:0000000000000000 [177.644][T2585409] RDX: 000000000000006d RSI: 0000000000000008 RDI:ffe21c006efd0f40 [177.655][T2585409] RBP: ff110002e0509f78 R08: 0000000000000001 R09:ffe21c006efd0f08 [177.665][T2585409] R10: ff11000377e87847 R11: 0000000000000000 R12:ff110002390cd9c0 [177.676][T2585409] R13: ff11000344b119c0 R14: ff110002e0508000 R15:dffffc0000000000 [177.687][T2585409] FS: 0000000000000000(0000) GS:ff11000fec880000(0000) knlGS:0000000000000000 [177.700][T2585409] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [177.709][T2585409] CR2: 00007f06bc7b1978 CR3: 0000001021e86005 CR4:0000000000771ef0 [177.720][T2585409] DR0: 0000000000000000 DR1: 0000000000000000 DR2:0000000000000000 [177.731][T2585409] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:0000000000000400 [177.742][T2585409] PKRU: 55555554 [177.748][T2585409] Call Trace: [177.753][T2585409] <TASK> [177.759][T2585409] ? __die_body.cold+0x19/0x27 [177.766][T2585409] ? die+0x2e/0x50 [177.772][T2585409] ? do_trap+0x1ea/0x2d0 [177.779][T2585409] ? __list_del_entry_valid_or_report.cold+0x70/0x72 [177.788][T2585409] ? do_error_trap+0xa3/0x160 [177.795][T2585409] ? __list_del_entry_valid_or_report.cold+0x70/0x72 [177.805][T2585409] ? handle_invalid_op+0x2c/0x40 [177.812][T2585409] ? __list_del_entry_valid_or_report.cold+0x70/0x72 [177.820][T2585409] ? exc_invalid_op+0x2d/0x40 [177.827][T2585409] ? asm_exc_invalid_op+0x1a/0x20 [177.834][T2585409] ? __list_del_entry_valid_or_report.cold+0x70/0x72 [177.843][T2585409] btrfs_delete_unused_bgs+0x3d9/0x14c0 [btrfs] There is a similar retry_list code in btrfs_delete_unused_bgs(), but it is safe, AFAICS. Since the block group was in the unused list, the used bytes should be 0 when it was added to the unused list. Then, it checks block_group->{used,reserved,pinned} are still 0 under the block_group->lock. So, they should be still eligible for the unused list, not the reclaim list. The reason it is safe there it's because because we're holding space_info->groups_sem in write mode. That means no other task can allocate from the block group, so while we are at deleted_unused_bgs() it's not possible for other tasks to allocate and deallocate extents from the block group, so it can't be added to the unused list or the reclaim list by anyone else. The bug can be reproduced by btrfs/166 after a few rounds. In practice this can be hit when relocation cannot find more chunk space and ends with ENOSPC.
The exploitability of CVE-2024-42103 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
CVE-2024-42103 presents an accessible attack vector with minimal effort required. Restricting access controls and implementing security updates are critical to reducing exploitation risks.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2024-42103, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2024-42103, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
The EPSS score estimates the probability that this vulnerability will be exploited in the near future.
EPSS Score: 0.045% (probability of exploit)
EPSS Percentile: 18.4%
(lower percentile = lower relative risk)
This vulnerability is less risky than approximately 81.6% of others.
NVD-CWE-noinfo
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