CVE-2025-21887

ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up

HIGH

7.8

CVSS Score

Published: March 27, 2025 at 02:57 PM UTC

Updated: October 15, 2026 at 02:17 AM UTC

4 products affected across 2 vendorsLinux KernelSIMATIC S7-1500 CPU 1518-4 Pn /dp MFP FirmwareSiplus S7-1500 CPU 1518-4 Pn /dp MFP Firmware

Using Linux by Linux?

Get instant alerts when new vulnerabilities affect Linux - before attackers find them.

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

HIGH7.8

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up The issue was caused by dput(upper) being called before ovl_dentry_update_reval(), while upper->d_flags was still accessed in ovl_dentry_remote(). Move dput(upper) after its last use to prevent use-after-free. BUG: KASAN: slab-use-after-free in ovl_dentry_remote fs/overlayfs/util.c:162 [inline] BUG: KASAN: slab-use-after-free in ovl_dentry_update_reval+0xd2/0xf0 fs/overlayfs/util.c:167 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0xc3/0x620 mm/kasan/report.c:488 kasan_report+0xd9/0x110 mm/kasan/report.c:601 ovl_dentry_remote fs/overlayfs/util.c:162 [inline] ovl_dentry_update_reval+0xd2/0xf0 fs/overlayfs/util.c:167 ovl_link_up fs/overlayfs/copy_up.c:610 [inline] ovl_copy_up_one+0x2105/0x3490 fs/overlayfs/copy_up.c:1170 ovl_copy_up_flags+0x18d/0x200 fs/overlayfs/copy_up.c:1223 ovl_rename+0x39e/0x18c0 fs/overlayfs/dir.c:1136 vfs_rename+0xf84/0x20a0 fs/namei.c:4893 ... </TASK>

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

95%

5.10.188 ≤ v < 5.115.15.121 ≤ v < 5.15.1796.1.39 ≤ v < 6.1.1306.13 ≤ v < 6.13.66.3.13 ≤ v < 6.46.4.4 ≤ v < 6.6.816.7 ≤ v < 6.12.181ecdc55e5cd9f70f8d7513802971d4cffb9f77af33ab4dd6202f359558a0a2678b94d1b9994c17e55.10.188 5.15.121 6.1.39 6.14 6.14 rc1 6.14 rc2 6.14 rc3 6.14 rc4 6.3.13 6.4.462f29ca45f832e281fc14966ac25f6ff3bd121ca714ba10a6dd19752a349e59aa875f3288ccb59b9b07d5cc93e1b28df47a72c519d09d0a836043613e4f2a1feebb3f209a0fca82aa53507a5b8be4d53

Vendor states this is fixed in 3594aad97e7be2557ca9fa9c931b206b604028c8 (fixed)

Vendor states this is fixed in 4b49d939b5a79117f939b77cc67efae2694d9799 (fixed)

Vendor states this is fixed in 60b4b5c1277fc491da9e1e7abab307bfa39c2db7 (fixed)

Vendor states this is fixed in 64455c8051c3aedc71abb7ec8d47c80301f99f00 (fixed)

Vendor states this is fixed in a7c41830ffcd17b2177a95a9b99b270302090c35 (fixed)

Vendor states this is fixed in c84e125fff2615b4d9c259e762596134eddd2f27 (fixed)

Vendor states this is fixed in f77618291836168eca99e89cd175256f928f5e64 (fixed)

Vendor states this is fixed in 5.10.247 (unaffected)

Affected range stops below 5.11, so it looks safe — our inference, not a vendor statement

Vendor states this is fixed in 5.15.179 (unaffected)

Vendor states this is fixed in 6.1.130 (unaffected)

Vendor states this is fixed in 6.12.18 (unaffected)