Security assessments indicate that CVE-2024-40962 presents a notable risk, potentially requiring prompt mitigation.
Status: Analyzed
Last updated: 🕓 07 Jan 2025, 16:10 UTC
Originally published on: 🕐 12 Jul 2024, 13:15 UTC
Time between publication and last update: 179 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-2024-40962: In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: allocate dummy checksums for zoned NODATASUM writes Shin'ichiro reported that when he's running fstests' test-case btrfs/167 on emulated zoned devices, he's seeing the following NULL pointer dereference in 'btrfs_zone_finish_endio()': Oops: general protection fault, probably for non-canonical address 0xdffffc0000000011: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f] CPU: 4 PID: 2332440 Comm: kworker/u80:15 Tainted: G W 6.10.0-rc2-kts+ #4 Hardware name: Supermicro Super Server/X11SPi-TF, BIOS 3.3 02/21/2020 Workqueue: btrfs-endio-write btrfs_work_helper [btrfs] RIP: 0010:btrfs_zone_finish_endio.part.0+0x34/0x160 [btrfs] RSP: 0018:ffff88867f107a90 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff893e5534 RDX: 0000000000000011 RSI: 0000000000000004 RDI: 0000000000000088 RBP: 0000000000000002 R08: 0000000000000001 R09: ffffed1081696028 R10: ffff88840b4b0143 R11: ffff88834dfff600 R12: ffff88840b4b0000 R13: 0000000000020000 R14: 0000000000000000 R15: ffff888530ad5210 FS: 0000000000000000(0000) GS:ffff888e3f800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f87223fff38 CR3: 00000007a7c6a002 CR4: 00000000007706f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> ? __die_body.cold+0x19/0x27 ? die_addr+0x46/0x70 ? exc_general_protection+0x14f/0x250 ? asm_exc_general_protection+0x26/0x30 ? do_raw_read_unlock+0x44/0x70 ? btrfs_zone_finish_endio.part.0+0x34/0x160 [btrfs] btrfs_finish_one_ordered+0x5d9/0x19a0 [btrfs] ? __pfx_lock_release+0x10/0x10 ? do_raw_write_lock+0x90/0x260 ? __pfx_do_raw_write_lock+0x10/0x10 ? __pfx_btrfs_finish_one_ordered+0x10/0x10 [btrfs] ? _raw_write_unlock+0x23/0x40 ? btrfs_finish_ordered_zoned+0x5a9/0x850 [btrfs] ? lock_acquire+0x435/0x500 btrfs_work_helper+0x1b1/0xa70 [btrfs] ? __schedule+0x10a8/0x60b0 ? __pfx___might_resched+0x10/0x10 process_one_work+0x862/0x1410 ? __pfx_lock_acquire+0x10/0x10 ? __pfx_process_one_work+0x10/0x10 ? assign_work+0x16c/0x240 worker_thread+0x5e6/0x1010 ? __pfx_worker_thread+0x10/0x10 kthread+0x2c3/0x3a0 ? trace_irq_enable.constprop.0+0xce/0x110 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x31/0x70 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Enabling CONFIG_BTRFS_ASSERT revealed the following assertion to trigger: assertion failed: !list_empty(&ordered->list), in fs/btrfs/zoned.c:1815 This indicates, that we're missing the checksums list on the ordered_extent. As btrfs/167 is doing a NOCOW write this is to be expected. Further analysis with drgn confirmed the assumption: >>> inode = prog.crashed_thread().stack_trace()[11]['ordered'].inode >>> btrfs_inode = drgn.container_of(inode, "struct btrfs_inode", \ "vfs_inode") >>> print(btrfs_inode.flags) (u32)1 As zoned emulation mode simulates conventional zones on regular devices, we cannot use zone-append for writing. But we're only attaching dummy checksums if we're doing a zone-append write. So for NOCOW zoned data writes on conventional zones, also attach a dummy checksum.
The exploitability of CVE-2024-40962 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-2024-40962 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-2024-40962, 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-2024-40962, 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: 0.042% (probability of exploit)
EPSS Percentile: 5.07%
(lower percentile = lower relative risk)
This vulnerability is less risky than approximately 94.93% of others.
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