Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2025-40295— fscrypt: fix left shift underflow when inode->i_blkbits > PAGE_SHIFT

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，该漏洞源于左移下溢，可能导致UBSAN警告。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.21% · P10

Possible ATT&CK Techniques 1 AI

T1498 · Network Denial of Service

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 47dd67532303803a87f43195e088b3b4bcf0454d< dde026c5d2a5870f97924d5b512adf2b93fb7153 affected
47dd67532303803a87f43195e088b3b4bcf0454d< 1e39da974ce621ed874c6d3aaf65ad14848c9f0d affected
6.15 affected
< 6.15 unaffected
6.17.8≤ 6.17.* unaffected
6.18≤ * unaffected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2025-40295

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
fscrypt: fix left shift underflow when inode->i_blkbits > PAGE_SHIFT
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: fscrypt: fix left shift underflow when inode->i_blkbits > PAGE_SHIFT When simulating an nvme device on qemu with both logical_block_size and physical_block_size set to 8 KiB, an error trace appears during partition table reading at boot time. The issue is caused by inode->i_blkbits being larger than PAGE_SHIFT, which leads to a left shift of -1 and triggering a UBSAN warning. [ 2.697306] ------------[ cut here ]------------ [ 2.697309] UBSAN: shift-out-of-bounds in fs/crypto/inline_crypt.c:336:37 [ 2.697311] shift exponent -1 is negative [ 2.697315] CPU: 3 UID: 0 PID: 274 Comm: (udev-worker) Not tainted 6.18.0-rc2+ #34 PREEMPT(voluntary) [ 2.697317] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 2.697320] Call Trace: [ 2.697324] <TASK> [ 2.697325] dump_stack_lvl+0x76/0xa0 [ 2.697340] dump_stack+0x10/0x20 [ 2.697342] __ubsan_handle_shift_out_of_bounds+0x1e3/0x390 [ 2.697351] bh_get_inode_and_lblk_num.cold+0x12/0x94 [ 2.697359] fscrypt_set_bio_crypt_ctx_bh+0x44/0x90 [ 2.697365] submit_bh_wbc+0xb6/0x190 [ 2.697370] block_read_full_folio+0x194/0x270 [ 2.697371] ? __pfx_blkdev_get_block+0x10/0x10 [ 2.697375] ? __pfx_blkdev_read_folio+0x10/0x10 [ 2.697377] blkdev_read_folio+0x18/0x30 [ 2.697379] filemap_read_folio+0x40/0xe0 [ 2.697382] filemap_get_pages+0x5ef/0x7a0 [ 2.697385] ? mmap_region+0x63/0xd0 [ 2.697389] filemap_read+0x11d/0x520 [ 2.697392] blkdev_read_iter+0x7c/0x180 [ 2.697393] vfs_read+0x261/0x390 [ 2.697397] ksys_read+0x71/0xf0 [ 2.697398] __x64_sys_read+0x19/0x30 [ 2.697399] x64_sys_call+0x1e88/0x26a0 [ 2.697405] do_syscall_64+0x80/0x670 [ 2.697410] ? __x64_sys_newfstat+0x15/0x20 [ 2.697414] ? x64_sys_call+0x204a/0x26a0 [ 2.697415] ? do_syscall_64+0xb8/0x670 [ 2.697417] ? irqentry_exit_to_user_mode+0x2e/0x2a0 [ 2.697420] ? irqentry_exit+0x43/0x50 [ 2.697421] ? exc_page_fault+0x90/0x1b0 [ 2.697422] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 2.697425] RIP: 0033:0x75054cba4a06 [ 2.697426] Code: 5d e8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 19 83 e2 39 83 fa 08 75 11 e8 26 ff ff ff 66 0f 1f 44 00 00 48 8b 45 10 0f 05 <48> 8b 5d f8 c9 c3 0f 1f 40 00 f3 0f 1e fa 55 48 89 e5 48 83 ec 08 [ 2.697427] RSP: 002b:00007fff973723a0 EFLAGS: 00000202 ORIG_RAX: 0000000000000000 [ 2.697430] RAX: ffffffffffffffda RBX: 00005ea9a2c02760 RCX: 000075054cba4a06 [ 2.697432] RDX: 0000000000002000 RSI: 000075054c190000 RDI: 000000000000001b [ 2.697433] RBP: 00007fff973723c0 R08: 0000000000000000 R09: 0000000000000000 [ 2.697434] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 [ 2.697434] R13: 00005ea9a2c027c0 R14: 00005ea9a2be5608 R15: 00005ea9a2be55f0 [ 2.697436] </TASK> [ 2.697436] ---[ end trace ]--- This situation can happen for block devices because when CONFIG_TRANSPARENT_HUGEPAGE is enabled, the maximum logical_block_size is 64 KiB. set_init_blocksize() then sets the block device inode->i_blkbits to 13, which is within this limit. File I/O does not trigger this problem because for filesystems that do not support the FS_LBS feature, sb_set_blocksize() prevents sb->s_blocksize_bits from being larger than PAGE_SHIFT. During inode allocation, alloc_inode()->inode_init_always() assigns inode->i_blkbits from sb->s_blocksize_bits. Currently, only xfs_fs_type has the FS_LBS flag, and since xfs I/O paths do not reach submit_bh_wbc(), it does not hit the left-shift underflow issue. [EB: use folio_pos() and consolidate the two shifts by i_blkbits]
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，该漏洞源于左移下溢，可能导致UBSAN警告。
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 47dd67532303803a87f43195e088b3b4bcf0454d ~ dde026c5d2a5870f97924d5b512adf2b93fb7153 -
Linux Linux 6.15 -

II. Public POCs for CVE-2025-40295

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2025-40295

请登录查看更多情报信息。

Same Patch Batch · Linux · 2025-12-08 · 82 CVEs total

CVE-2023-53751 9.8 CRITICAL cifs: fix potential use-after-free bugs in TCP_Server_Info::hostname
CVE-2025-40320 9.8 CRITICAL smb: client: fix potential cfid UAF in smb2_query_info_compound
CVE-2023-53769 9.3 CRITICAL virt/coco/sev-guest: Double-buffer messages
CVE-2023-53764 8.8 HIGH wifi: ath12k: Handle lock during peer_id find
CVE-2023-53762 8.8 HIGH Bluetooth: hci_sync: Fix UAF in hci_disconnect_all_sync
CVE-2025-40318 8.8 HIGH Bluetooth: hci_sync: fix race in hci_cmd_sync_dequeue_once
CVE-2025-40292 8.4 HIGH virtio-net: fix received length check in big packets
CVE-2025-40309 8.0 HIGH Bluetooth: SCO: Fix UAF on sco_conn_free
CVE-2025-40302 7.8 HIGH media: videobuf2: forbid remove_bufs when legacy fileio is active
CVE-2025-40317 7.8 HIGH regmap: slimbus: fix bus_context pointer in regmap init calls
CVE-2025-40303 7.8 HIGH btrfs: ensure no dirty metadata is written back for an fs with errors
CVE-2023-53763 7.8 HIGH Revert "f2fs: fix to do sanity check on extent cache correctly"
CVE-2023-53759 7.8 HIGH HID: hidraw: fix data race on device refcount
CVE-2025-40319 7.8 HIGH bpf: Sync pending IRQ work before freeing ring buffer
CVE-2025-40323 7.8 HIGH fbcon: Set fb_display[i]->mode to NULL when the mode is released
CVE-2023-53753 7.8 HIGH drm/amd/display: fix mapping to non-allocated address
CVE-2023-53752 7.8 HIGH net: deal with integer overflows in kmalloc_reserve()
CVE-2023-53747 7.8 HIGH vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF
CVE-2022-50623 7.8 HIGH fpga: prevent integer overflow in dfl_feature_ioctl_set_irq()
CVE-2022-50630 7.8 HIGH mm: hugetlb: fix UAF in hugetlb_handle_userfault

Showing top 20 of 82 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-40295

No comments yet

Leave a comment