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CVE-2025-40138— f2fs: fix to avoid NULL pointer dereference in f2fs_check_quota_consistency()

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存在安全漏洞，该漏洞源于未检查配额一致性，可能导致空指针取消引用。

AI Predicted 5.5 Difficulty: Easy EPSS 0.20% · P9

Possible ATT&CK Techniques 1 AI

T1498 · Network Denial of Service

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux d185351325237da688de006a2c579e82ea97bdfe< 3f3458852bbfe79c60f2412b8b04677b96688b6e affected
d185351325237da688de006a2c579e82ea97bdfe< 930a9a6ee8e7ffa20af4bffbfc2bbd21d83bf81c affected
6.17 affected
< 6.17 unaffected
6.17.3≤ 6.17.* unaffected
6.18≤ * unaffected
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I. Basic Information for CVE-2025-40138

Vulnerability Information
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Vulnerability Title
f2fs: fix to avoid NULL pointer dereference in f2fs_check_quota_consistency()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid NULL pointer dereference in f2fs_check_quota_consistency() syzbot reported a f2fs bug as below: Oops: gen[ 107.736417][ T5848] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 UID: 0 PID: 5848 Comm: syz-executor263 Tainted: G W 6.17.0-rc1-syzkaller-00014-g0e39a731820a #0 PREEMPT_{RT,(full)} RIP: 0010:strcmp+0x3c/0xc0 lib/string.c:284 Call Trace: <TASK> f2fs_check_quota_consistency fs/f2fs/super.c:1188 [inline] f2fs_check_opt_consistency+0x1378/0x2c10 fs/f2fs/super.c:1436 __f2fs_remount fs/f2fs/super.c:2653 [inline] f2fs_reconfigure+0x482/0x1770 fs/f2fs/super.c:5297 reconfigure_super+0x224/0x890 fs/super.c:1077 do_remount fs/namespace.c:3314 [inline] path_mount+0xd18/0xfe0 fs/namespace.c:4112 do_mount fs/namespace.c:4133 [inline] __do_sys_mount fs/namespace.c:4344 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4321 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The direct reason is f2fs_check_quota_consistency() may suffer null-ptr-deref issue in strcmp(). The bug can be reproduced w/ below scripts: mkfs.f2fs -f /dev/vdb mount -t f2fs -o usrquota /dev/vdb /mnt/f2fs quotacheck -uc /mnt/f2fs/ umount /mnt/f2fs mount -t f2fs -o usrjquota=aquota.user,jqfmt=vfsold /dev/vdb /mnt/f2fs mount -t f2fs -o remount,usrjquota=,jqfmt=vfsold /dev/vdb /mnt/f2fs umount /mnt/f2fs So, before old_qname and new_qname comparison, we need to check whether they are all valid pointers, fix it.
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 安全漏洞
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存在安全漏洞，该漏洞源于未检查配额一致性，可能导致空指针取消引用。
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 d185351325237da688de006a2c579e82ea97bdfe ~ 3f3458852bbfe79c60f2412b8b04677b96688b6e -
Linux Linux 6.17 -

II. Public POCs for CVE-2025-40138

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III. Intelligence Information for CVE-2025-40138

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Same Patch Batch · Linux · 2025-11-12 · 96 CVEs total

CVE-2025-40176 9.8 CRITICAL tls: wait for pending async decryptions if tls_strp_msg_hold fails
CVE-2025-40140 8.8 HIGH net: usb: Remove disruptive netif_wake_queue in rtl8150_set_multicast
CVE-2025-40133 8.1 HIGH mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().
CVE-2025-40186 8.1 HIGH tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request().
CVE-2025-40158 8.1 HIGH ipv6: use RCU in ip6_output()
CVE-2025-40204 8.1 HIGH sctp: Fix MAC comparison to be constant-time
CVE-2025-40135 8.1 HIGH ipv6: use RCU in ip6_xmit()
CVE-2025-40168 8.1 HIGH smc: Use __sk_dst_get() and dst_dev_rcu() in smc_clc_prfx_match().
CVE-2025-40141 8.0 HIGH Bluetooth: ISO: Fix possible UAF on iso_conn_free
CVE-2025-40166 7.8 HIGH drm/xe/guc: Check GuC running state before deregistering exec queue
CVE-2025-40159 7.8 HIGH xsk: Harden userspace-supplied xdp_desc validation
CVE-2025-40173 7.8 HIGH net/ip6_tunnel: Prevent perpetual tunnel growth
CVE-2025-40167 7.8 HIGH ext4: detect invalid INLINE_DATA + EXTENTS flag combination
CVE-2025-40170 7.8 HIGH net: use dst_dev_rcu() in sk_setup_caps()
CVE-2025-40149 7.8 HIGH tls: Use __sk_dst_get() and dst_dev_rcu() in get_netdev_for_sock().
CVE-2025-40172 7.8 HIGH accel/qaic: Treat remaining == 0 as error in find_and_map_user_pages()
CVE-2025-40174 7.8 HIGH x86/mm: Fix SMP ordering in switch_mm_irqs_off()
CVE-2025-40139 7.8 HIGH smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().
CVE-2025-40190 7.8 HIGH ext4: guard against EA inode refcount underflow in xattr update
CVE-2025-40151 7.8 HIGH LoongArch: BPF: No support of struct argument in trampoline programs

Showing top 20 of 96 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-40138

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