ext4: fix OOB read when checking dotdot dir

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-37785
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-04-18 07:15:42 UTC
Updated2026-07-14 13:17:33 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ext4: fix OOB read when checking dotdot dir Mounting a corrupted filesystem with directory which contains '.' dir entry with rec_len == block size results in out-of-bounds read (later on, when the corrupted directory is removed). ext4_empty_dir() assumes every ext4 directory contains at least '.' and '..' as directory entries in the first data block. It first loads the '.' dir entry, performs sanity checks by calling ext4_check_dir_entry() and then uses its rec_len member to compute the location of '..' dir entry (in ext4_next_entry). It assumes the '..' dir entry fits into the same data block. If the rec_len of '.' is precisely one block (4KB), it slips through the sanity checks (it is considered the last directory entry in the data block) and leaves "struct ext4_dir_entry_2 *de" point exactly past the memory slot allocated to the data block. The following call to ext4_check_dir_entry() on new value of de then dereferences this pointer which results in out-of-bounds mem access. Fix this by extending __ext4_check_dir_entry() to check for '.' dir entries that reach the end of data block. Make sure to ignore the phony dir entries for checksum (by checking name_len for non-zero). Note: This is reported by KASAN as use-after-free in case another structure was recently freed from the slot past the bound, but it is really an OOB read. This issue was found by syzkaller tool. Call Trace: [ 38.594108] BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x67e/0x710 [ 38.594649] Read of size 2 at addr ffff88802b41a004 by task syz-executor/5375 [ 38.595158] [ 38.595288] CPU: 0 UID: 0 PID: 5375 Comm: syz-executor Not tainted 6.14.0-rc7 #1 [ 38.595298] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 38.595304] Call Trace: [ 38.595308] <TASK> [ 38.595311] dump_stack_lvl+0xa7/0xd0 [ 38.595325] print_address_description.constprop.0+0x2c/0x3f0 [ 38.595339] ? __ext4_check_dir_entry+0x67e/0x710 [ 38.595349] print_report+0xaa/0x250 [ 38.595359] ? __ext4_check_dir_entry+0x67e/0x710 [ 38.595368] ? kasan_addr_to_slab+0x9/0x90 [ 38.595378] kasan_report+0xab/0xe0 [ 38.595389] ? __ext4_check_dir_entry+0x67e/0x710 [ 38.595400] __ext4_check_dir_entry+0x67e/0x710 [ 38.595410] ext4_empty_dir+0x465/0x990 [ 38.595421] ? __pfx_ext4_empty_dir+0x10/0x10 [ 38.595432] ext4_rmdir.part.0+0x29a/0xd10 [ 38.595441] ? __dquot_initialize+0x2a7/0xbf0 [ 38.595455] ? __pfx_ext4_rmdir.part.0+0x10/0x10 [ 38.595464] ? __pfx___dquot_initialize+0x10/0x10 [ 38.595478] ? down_write+0xdb/0x140 [ 38.595487] ? __pfx_down_write+0x10/0x10 [ 38.595497] ext4_rmdir+0xee/0x140 [ 38.595506] vfs_rmdir+0x209/0x670 [ 38.595517] ? lookup_one_qstr_excl+0x3b/0x190 [ 38.595529] do_rmdir+0x363/0x3c0 [ 38.595537] ? __pfx_do_rmdir+0x10/0x10 [ 38.595544] ? strncpy_from_user+0x1ff/0x2e0 [ 38.595561] __x64_sys_unlinkat+0xf0/0x130 [ 38.595570] do_syscall_64+0x5b/0x180 [ 38.595583] entry_SYSCALL_64_after_hwframe+0x76/0x7e

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Problem Types: CWE-125

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected ac27a0ec112a089f1a5102bc8dffc79c8c815571 14da7dbecb430e35b5889da8dae7bef33173b351 git Not specified
CNA Linux Linux affected ac27a0ec112a089f1a5102bc8dffc79c8c815571 e47f472a664d70a3d104a6c2a035cdff55a719b4 git Not specified
CNA Linux Linux affected ac27a0ec112a089f1a5102bc8dffc79c8c815571 b7531a4f99c3887439d778afaf418d1a01a5f01b git Not specified
CNA Linux Linux affected ac27a0ec112a089f1a5102bc8dffc79c8c815571 89503e5eae64637d0fa2218912b54660effe7d93 git Not specified
CNA Linux Linux affected ac27a0ec112a089f1a5102bc8dffc79c8c815571 52a5509ab19a5d3afe301165d9b5787bba34d842 git Not specified
CNA Linux Linux affected ac27a0ec112a089f1a5102bc8dffc79c8c815571 b47584c556444cf7acb66b26a62cbc348eb92b78 git Not specified
CNA Linux Linux affected ac27a0ec112a089f1a5102bc8dffc79c8c815571 ac28c5684c1cdab650a7e5065b19e91577d37a4b git Not specified
CNA Linux Linux affected ac27a0ec112a089f1a5102bc8dffc79c8c815571 53bc45da8d8da92ec07877f5922b130562eb4b00 git Not specified
CNA Linux Linux affected ac27a0ec112a089f1a5102bc8dffc79c8c815571 d5e206778e96e8667d3bde695ad372c296dc9353 git Not specified
CNA Linux Linux affected 2.6.19 Not specified
CNA Linux Linux unaffected 2.6.19 semver Not specified
CNA Linux Linux unaffected 5.4.293 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.236 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.180 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.134 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.87 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.23 6.12.* semver Not specified
CNA Linux Linux unaffected 6.13.11 6.13.* semver Not specified
CNA Linux Linux unaffected 6.14.2 6.14.* semver Not specified
CNA Linux Linux unaffected 6.15 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified

References

ReferenceSourceLinkTags
lists.debian.org/debian-lts-announce/2025/05/msg00030.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
git.kernel.org/stable/c/d5e206778e96e8667d3bde695ad372c296dc9353 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/52a5509ab19a5d3afe301165d9b5787bba34d842 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/b47584c556444cf7acb66b26a62cbc348eb92b78 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/e47f472a664d70a3d104a6c2a035cdff55a719b4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/ac28c5684c1cdab650a7e5065b19e91577d37a4b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/05/msg00045.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
git.kernel.org/stable/c/53bc45da8d8da92ec07877f5922b130562eb4b00 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/89503e5eae64637d0fa2218912b54660effe7d93 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/14da7dbecb430e35b5889da8dae7bef33173b351 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b7531a4f99c3887439d778afaf418d1a01a5f01b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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