Description
In the Linux kernel, the following vulnerability has been resolved:
fs/notify: call exportfs_encode_fid with s_umount
Calling intotify_show_fdinfo() on fd watching an overlayfs inode, while
the overlayfs is being unmounted, can lead to dereferencing NULL ptr.
This issue was found by syzkaller.
Race Condition Diagram:
Thread 1 Thread 2
-------- --------
generic_shutdown_super()
shrink_dcache_for_umount
sb->s_root = NULL
|
| vfs_read()
| inotify_fdinfo()
| * inode get from mark *
| show_mark_fhandle(m, inode)
| exportfs_encode_fid(inode, ..)
| ovl_encode_fh(inode, ..)
| ovl_check_encode_origin(inode)
| * deref i_sb->s_root *
|
|
v
fsnotify_sb_delete(sb)
Which then leads to:
[ 32.133461] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
[ 32.134438] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
[ 32.135032] CPU: 1 UID: 0 PID: 4468 Comm: systemd-coredum Not tainted 6.17.0-rc6 #22 PREEMPT(none)
<snip registers, unreliable trace>
[ 32.143353] Call Trace:
[ 32.143732] ovl_encode_fh+0xd5/0x170
[ 32.144031] exportfs_encode_inode_fh+0x12f/0x300
[ 32.144425] show_mark_fhandle+0xbe/0x1f0
[ 32.145805] inotify_fdinfo+0x226/0x2d0
[ 32.146442] inotify_show_fdinfo+0x1c5/0x350
[ 32.147168] seq_show+0x530/0x6f0
[ 32.147449] seq_read_iter+0x503/0x12a0
[ 32.148419] seq_read+0x31f/0x410
[ 32.150714] vfs_read+0x1f0/0x9e0
[ 32.152297] ksys_read+0x125/0x240
IOW ovl_check_encode_origin derefs inode->i_sb->s_root, after it was set
to NULL in the unmount path.
Fix it by protecting calling exportfs_encode_fid() from
show_mark_fhandle() with s_umount lock.
This form of fix was suggested by Amir in [1].
[1]: https://lore.kernel.org/all/CAOQ4uxhbDwhb+2Brs1UdkoF0a3NSdBAOQPNfEHjahrgoKJpLEw@mail.gmail.com/
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 6.6.72 – < 6.6.73, 6.6.74 – < 6.6.115, 6.12.10 – < 6.12.56, 6.13 | 6.6.73 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 6.17.6-1 | — |
| Debian 13 | linux | 6.12.57-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Nvidia-BlueField 24.04 LTS | linux-bluefield | 6.8.0-1017.21 | — |
| Ubuntu 25.10 | linux | 6.17.0-14.14 | USN-8029-1 |
| Ubuntu 25.10 | linux-aws +2 | 6.17.0-1007.7 | USN-8030-1, USN-8029-2 |
| Ubuntu 25.10 | linux-azure +1 | 6.17.0-1008.8 | USN-8029-3, USN-8029-1 |
| Ubuntu 25.10 | linux-azure-fde | No fix yet | — |
| Ubuntu 25.10 | linux-realtime | 6.17.0-1006.7 | USN-8029-1 |
| Ubuntu 25.10 | linux-riscv | 6.17.0-14.14.1 | — |
| Ubuntu 24.04 LTS | linux | 6.8.0-106.106 | USN-8095-1 |
| Ubuntu 24.04 LTS | linux-aws | 6.8.0-1050.53 | USN-8095-1 |
| Ubuntu 24.04 LTS | linux-aws-6.17 +1 | 6.17.0-1007.7~24.04.1 | — |
| Ubuntu 24.04 LTS | linux-azure | 6.8.0-1051.57 | USN-8125-1 |
| Ubuntu 24.04 LTS | linux-azure-fde | 6.8.0-1058.65 | — |
| Ubuntu 24.04 LTS | linux-azure-nvidia | 6.8.0-1039.42 | — |
| Ubuntu 24.04 LTS | linux-gcp | 6.8.0-1052.55 | USN-8095-1 |
| Ubuntu 24.04 LTS | linux-gcp-6.17 | 6.17.0-1008.8~24.04.1 | — |
| Ubuntu 24.04 LTS | linux-gke | 6.8.0-1048.53 | USN-8095-1 |
| Ubuntu 24.04 LTS | linux-gkeop | 6.8.0-1035.38 | USN-8095-1 |
| Ubuntu 24.04 LTS | linux-ibm | 6.8.0-1049.49 | USN-8095-1 |
| Ubuntu 24.04 LTS | linux-lowlatency | 6.8.0-106.106.1 | USN-8095-1 |
| Ubuntu 24.04 LTS | linux-nvidia | 6.8.0-1049.52 | USN-8100-1 |
| Ubuntu 24.04 LTS | linux-nvidia-6.17 | 6.17.0-1008.8 | — |
| Ubuntu 24.04 LTS | linux-nvidia-lowlatency | 6.8.0-1049.52.1 | USN-8100-1 |
| Ubuntu 24.04 LTS | linux-nvidia-tegra | 6.8.0-1020.20 | — |
| Ubuntu 24.04 LTS | linux-oem-6.17 | 6.17.0-1011.11 | USN-8048-1 |
| Ubuntu 24.04 LTS | linux-oracle | 6.8.0-1047.48 | USN-8095-1 |
| Ubuntu 24.04 LTS | linux-raspi | 6.8.0-1050.54 | USN-8095-5 |
| Ubuntu 24.04 LTS | linux-riscv +18 | No fix yet | — |
| Ubuntu 24.04 LTS | linux-xilinx | 6.8.0-1028.29 | USN-8261-1 |
| Ubuntu 22.04 LTS | linux-aws-6.8 | 6.8.0-1050.53~22.04.1 | USN-8095-4 |
| Ubuntu 22.04 LTS | linux-azure-6.8 | 6.8.0-1051.57~22.04.1 | USN-8126-1 |
| Ubuntu 22.04 LTS | linux-azure-fde-6.8 | 6.8.0-1058.65~22.04.1 | — |
| Ubuntu 22.04 LTS | linux-gcp-6.8 | 6.8.0-1052.55~22.04.1 | USN-8095-1 |
| Ubuntu 22.04 LTS | linux-hwe-6.8 +1 | 6.8.0-106.106~22.04.1 | USN-8095-1 |
| Ubuntu 22.04 LTS | linux-ibm-6.8 | 6.8.0-1049.49~22.04.1 | USN-8095-1 |
| Ubuntu 22.04 LTS | linux-lowlatency-hwe-6.8 | 6.8.0-106.106.1~22.04.1 | USN-8095-1 |
| Ubuntu 22.04 LTS | linux-nvidia-6.8 | 6.8.0-1049.52~22.04.1 | USN-8100-1 |
| Ubuntu 22.04 LTS | linux-oracle-6.8 | 6.8.0-1047.48~22.04.1 | USN-8095-1 |
| Ubuntu 22.04 LTS | linux-riscv +32 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +28 | No fix yet | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | linux-gcp +14 | No fix yet | — |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-raspi-realtime | 6.8.0-2040.41 | USN-8095-5 |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime | 6.8.1-1045.46 | USN-8095-3 |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime-6.14 | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime-6.17 | 6.17.0-1006.7~24.04.1 | — |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime-6.8 | 6.8.1-1045.46~22.04.1 | USN-8095-3 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-aws-fips | 6.8.0-1050.53+fips1 | USN-8095-2 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-azure-fips | 6.8.0-1052.58+fips1 | USN-8165-1 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-fips | 6.8.0-106.106+fips1 | USN-8095-2 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-gcp-fips | 6.8.0-1052.55+fips1 | USN-8095-2 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | rv +76 | 6.12.0-211.39.1.el10_2 | RHSA-2026:45114 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10.0 EUS | rv +77 | 6.12.0-55.109.1.el10_0 | RHSA-2026:77634 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | rv +74 | 6.12.0-211.39.1.el10_2 | ALSA-2026:45114 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | kernel | 6.12.0-211.39.1.el10_2 | RLSA-2026:45114 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | kernel-64kb +8 | 6.12.0-160000.9.1 | SUSE-SU-2026:20220-1 |
| SLES for SAP 16.0 | kernel-default-base | 6.12.0-160000.9.1.160000.2.6 | SUSE-SU-2026:20220-1 |
| SLES 16.0 | kernel-64kb +8 | 6.12.0-160000.9.1 | SUSE-SU-2026:20228-1, SUSE-SU-2026:20220-1 |
| SLES 16.0 | kernel-default-base | 6.12.0-160000.9.1.160000.2.6 | SUSE-SU-2026:20220-1 |
| SLE Micro 6.2 | kernel-default-base | 6.12.0-160000.9.1.160000.2.6 | SUSE-SU-2026:20207-1 |
| SLE Micro 6.2 | kernel-rt +5 | 6.12.0-160000.9.1 | SUSE-SU-2026:20564-1, SUSE-SU-2026:20207-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | kernel-default-base | 6.12.0-160000.9.1.160000.2.6 | openSUSE-SU-2026:20145-1 |
| openSUSE Leap 16.0 | kernel-rt +11 | 6.12.0-160000.9.1 | openSUSE-SU-2026:20145-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | kernel-livepatch-6.12.58-82.121 | 1:1.0-0.amzn2023 | ALAS2023-2026-1495 |
| Amazon Linux 2023 | perf6.12 +14 | 1:6.12.58-82.121.amzn2023 | ALAS2023-2026-1495 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | rv +29 | 6.12.0-211.39.1.el10_2 | ELSA-2026-45114 |
| Oracle Linux 9 | kernel-uek +34 | 6.12.0-107.59.3.2.el10uek | ELSA-2026-50006 |
Advisories 28
- USN-8100-1 linux-nvidia, linux-nvidia-6.8, linux-nvidia-lowlatency vulnerabilities Ubuntu Security Notices (USN) · Nov 4, 2026
- USN-8165-1 linux-azure-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 4, 2026
- WID-SEC-2025-2747 Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service BSI CERT-Bund (WID) · Nov 3, 2026
- USN-8095-1 linux, linux-aws, linux-gcp, linux-gcp-6.8, linux-gke, linux-gkeop, linux-hwe-6.8, linux-ibm, linux-ibm-6.8, linux-lowlatency, linux-lowlatency-hwe-6.8, linux-oracle, linux-oracle-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8095-2 linux-fips, linux-aws-fips, linux-gcp-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8126-1 linux-azure-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8095-5 linux-raspi, linux-raspi-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8125-1 linux-azure vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8095-4 linux-aws-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8029-2 linux-aws, linux-oracle vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8048-1 linux-oem-6.17 vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8029-3 linux-azure vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8030-1 linux-gcp vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8029-1 linux, linux-raspi, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-8095-3 linux-realtime, linux-realtime-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- ALSA-2026:45114 Important: kernel security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2026:77634 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:45114 Red Hat Security Advisory: kernel security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- USN-8261-1 linux-xilinx vulnerabilities Ubuntu Security Notices (USN) · Sep 7, 2026
- ELSA-2026-45114 Important: kernel security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Jul 29, 2026
- RLSA-2026:45114 Important: kernel security update Rocky Linux Security Advisories · Jul 27, 2026
- SUSE-SU-2026:20564-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Jul 9, 2026
- ALAS2023-2026-1495 Important: kernel6.12 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Mar 27, 2026
- openSUSE-SU-2026:20145-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:20228-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:20207-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:20220-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Mar 23, 2026
- ELSA-2026-50006 Important: Unbreakable Enterprise kernel security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Jan 13, 2026
References
- https://git.kernel.org/stable/c/950b604384fd75d62e860bec7135b2b62eb4d508
- https://git.kernel.org/stable/c/bc1c6b803e14ea2b8f7e33b7164013f666ceb656
- https://git.kernel.org/stable/c/3f307a9f7a7a2822e38ac451b73e2244e7279496
- https://git.kernel.org/stable/c/d1894bc542becb0fda61e7e513b09523cab44030
- https://git.kernel.org/stable/c/a7c4bb43bfdc2b9f06ee9d036028ed13a83df42a