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CVE-2025-21658— btrfs: avoid NULL pointer dereference if no valid extent tree

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在代码问题漏洞，该漏洞源于btrfs模块在scrub操作中未检查extent tree的有效性。这可能导致空指针解引用或系统崩溃。

AI Predicted 6.5 Difficulty: Hard EPSS 0.20% · P10

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 42437a6386ffeaaf200731e73d723ea491f3fe7d< 24b85a8b0310e0144da9ab30be42e87e6476638a affected
42437a6386ffeaaf200731e73d723ea491f3fe7d< aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784 affected
42437a6386ffeaaf200731e73d723ea491f3fe7d< 6aecd91a5c5b68939cf4169e32bc49f3cd2dd329 affected
5.11 affected
< 5.11 unaffected
6.6.72≤ 6.6.* unaffected
6.12.10≤ 6.12.* unaffected
6.13≤ * unaffected
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I. Basic Information for CVE-2025-21658

Vulnerability Information
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Vulnerability Title
btrfs: avoid NULL pointer dereference if no valid extent tree
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: avoid NULL pointer dereference if no valid extent tree [BUG] Syzbot reported a crash with the following call trace: BTRFS info (device loop0): scrub: started on devid 1 BUG: kernel NULL pointer dereference, address: 0000000000000208 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 106e70067 P4D 106e70067 PUD 107143067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 UID: 0 PID: 689 Comm: repro Kdump: loaded Tainted: G O 6.13.0-rc4-custom+ #206 Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:find_first_extent_item+0x26/0x1f0 [btrfs] Call Trace: <TASK> scrub_find_fill_first_stripe+0x13d/0x3b0 [btrfs] scrub_simple_mirror+0x175/0x260 [btrfs] scrub_stripe+0x5d4/0x6c0 [btrfs] scrub_chunk+0xbb/0x170 [btrfs] scrub_enumerate_chunks+0x2f4/0x5f0 [btrfs] btrfs_scrub_dev+0x240/0x600 [btrfs] btrfs_ioctl+0x1dc8/0x2fa0 [btrfs] ? do_sys_openat2+0xa5/0xf0 __x64_sys_ioctl+0x97/0xc0 do_syscall_64+0x4f/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> [CAUSE] The reproducer is using a corrupted image where extent tree root is corrupted, thus forcing to use "rescue=all,ro" mount option to mount the image. Then it triggered a scrub, but since scrub relies on extent tree to find where the data/metadata extents are, scrub_find_fill_first_stripe() relies on an non-empty extent root. But unfortunately scrub_find_fill_first_stripe() doesn't really expect an NULL pointer for extent root, it use extent_root to grab fs_info and triggered a NULL pointer dereference. [FIX] Add an extra check for a valid extent root at the beginning of scrub_find_fill_first_stripe(). The new error path is introduced by 42437a6386ff ("btrfs: introduce mount option rescue=ignorebadroots"), but that's pretty old, and later commit b979547513ff ("btrfs: scrub: introduce helper to find and fill sector info for a scrub_stripe") changed how we do scrub. So for kernels older than 6.6, the fix will need manual backport.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在代码问题漏洞，该漏洞源于btrfs模块在scrub操作中未检查extent tree的有效性。这可能导致空指针解引用或系统崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 42437a6386ffeaaf200731e73d723ea491f3fe7d ~ 24b85a8b0310e0144da9ab30be42e87e6476638a -
Linux Linux 5.11 -

II. Public POCs for CVE-2025-21658

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III. Intelligence Information for CVE-2025-21658

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Patches & Fixes for CVE-2025-21658 (3)

Same Patch Batch · Linux · 2025-01-21 · 25 CVEs total

CVE-2025-21663 10.0 CRITICAL net: stmmac: dwmac-tegra: Read iommu stream id from device tree
CVE-2024-57932 9.8 CRITICAL gve: guard XDP xmit NDO on existence of xdp queues
CVE-2024-57936 9.8 CRITICAL RDMA/bnxt_re: Fix max SGEs for the Work Request
CVE-2025-21659 8.1 HIGH netdev: prevent accessing NAPI instances from another namespace
CVE-2025-21664 7.8 HIGH dm thin: make get_first_thin use rcu-safe list first function
CVE-2025-21661 7.8 HIGH gpio: virtuser: fix missing lookup table cleanups
CVE-2024-57945 7.8 HIGH riscv: mm: Fix the out of bound issue of vmemmap address
CVE-2024-57943 exfat: fix the new buffer was not zeroed before writing
CVE-2024-57946 virtio-blk: don't keep queue frozen during system suspend
CVE-2025-21662 net/mlx5: Fix variable not being completed when function returns
CVE-2025-21660 ksmbd: fix unexpectedly changed path in ksmbd_vfs_kern_path_locked
CVE-2025-21657 sched_ext: Replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass()
CVE-2025-21656 hwmon: (drivetemp) Fix driver producing garbage data when SCSI errors occur
CVE-2024-57944 iio: adc: ti-ads1298: Add NULL check in ads1298_init
CVE-2024-57930 tracing: Have process_string() also allow arrays
CVE-2024-57942 netfs: Fix ceph copy to cache on write-begin
CVE-2024-57941 netfs: Fix the (non-)cancellation of copy when cache is temporarily disabled
CVE-2024-57940 exfat: fix the infinite loop in exfat_readdir()
CVE-2024-57939 riscv: Fix sleeping in invalid context in die()
CVE-2024-57938 net/sctp: Prevent autoclose integer overflow in sctp_association_init()

Showing top 20 of 25 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-21658

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