ext4: fix string copying in parse_apply_sb_mount_options()

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Summary

CVECVE-2025-71123
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-14 15:16:02 UTC
Updated2026-07-14 13:18:03 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ext4: fix string copying in parse_apply_sb_mount_options() strscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term string of possibly bigger size. Commit 0efc5990bca5 ("string.h: Introduce memtostr() and memtostr_pad()") provides additional information in that regard. So if this happens, the following warning is observed: strnlen: detected buffer overflow: 65 byte read of buffer size 64 WARNING: CPU: 0 PID: 28655 at lib/string_helpers.c:1032 __fortify_report+0x96/0xc0 lib/string_helpers.c:1032 Modules linked in: CPU: 0 UID: 0 PID: 28655 Comm: syz-executor.3 Not tainted 6.12.54-syzkaller-00144-g5f0270f1ba00 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__fortify_report+0x96/0xc0 lib/string_helpers.c:1032 Call Trace: <TASK> __fortify_panic+0x1f/0x30 lib/string_helpers.c:1039 strnlen include/linux/fortify-string.h:235 [inline] sized_strscpy include/linux/fortify-string.h:309 [inline] parse_apply_sb_mount_options fs/ext4/super.c:2504 [inline] __ext4_fill_super fs/ext4/super.c:5261 [inline] ext4_fill_super+0x3c35/0xad00 fs/ext4/super.c:5706 get_tree_bdev_flags+0x387/0x620 fs/super.c:1636 vfs_get_tree+0x93/0x380 fs/super.c:1814 do_new_mount fs/namespace.c:3553 [inline] path_mount+0x6ae/0x1f70 fs/namespace.c:3880 do_mount fs/namespace.c:3893 [inline] __do_sys_mount fs/namespace.c:4103 [inline] __se_sys_mount fs/namespace.c:4080 [inline] __x64_sys_mount+0x280/0x300 fs/namespace.c:4080 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x64/0x140 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x76/0x7e Since userspace is expected to provide s_mount_opts field to be at most 63 characters long with the ending byte being NUL-term, use a 64-byte buffer which matches the size of s_mount_opts, so that strscpy_pad() does its job properly. Return with error if the user still managed to provide a non-NUL-term string here. Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

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

Problem Types: NVD-CWE-noinfo

CVSS v3.1 Breakdown

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

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 b2bac84fde28fb6a88817b8b761abda17a1d300b 52ac96c4a2dd7bc47666000440b0602d9742e820 git Not specified
CNA Linux Linux affected e651294218d2684302ee5ed95ccf381646f3e5b4 6e37143560e37869d51b7d9e0ac61fc48895f8a0 git Not specified
CNA Linux Linux affected 01829af7656b56d83682b3491265d583d502e502 902ca2356f1e3ec5355c5808ad5d3f9d0095b0cc git Not specified
CNA Linux Linux affected 2a0cf438320cdb783e0378570744c0ef0d83e934 db9ee13fab0267eccf6544ee35b16c9522db9aac git Not specified
CNA Linux Linux affected 8ecb790ea8c3fc69e77bace57f14cf0d7c177bd8 5bbacbbf1ca4419861dca3c6b82707c10e9c021c git Not specified
CNA Linux Linux affected 8ecb790ea8c3fc69e77bace57f14cf0d7c177bd8 ee5a977b4e771cc181f39d504426dbd31ed701cc git Not specified
CNA Linux Linux affected 7bf46ff83a0ef11836e38ebd72cdc5107209342d git Not specified
CNA Linux Linux affected a6e94557cd05adc82fae0400f6e17745563e5412 git Not specified
CNA Linux Linux affected 5.10.246 5.10.248 semver Not specified
CNA Linux Linux affected 6.1.158 6.1.160 semver Not specified
CNA Linux Linux affected 6.6.114 6.6.120 semver Not specified
CNA Linux Linux affected 6.12.54 6.12.64 semver Not specified
CNA Linux Linux affected 5.4.301 5.5 semver Not specified
CNA Linux Linux affected 6.17.4 6.18 semver Not specified
CNA Linux Linux affected 6.18 Not specified
CNA Linux Linux unaffected 6.18 semver Not specified
CNA Linux Linux unaffected 5.10.248 5.10.* semver Not specified
CNA Linux Linux unaffected 6.1.160 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.120 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.64 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.3 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19 * 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
git.kernel.org/stable/c/ee5a977b4e771cc181f39d504426dbd31ed701cc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/db9ee13fab0267eccf6544ee35b16c9522db9aac 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/902ca2356f1e3ec5355c5808ad5d3f9d0095b0cc 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/52ac96c4a2dd7bc47666000440b0602d9742e820 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/5bbacbbf1ca4419861dca3c6b82707c10e9c021c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/6e37143560e37869d51b7d9e0ac61fc48895f8a0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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