CVE-2023-53791
NoneCVSS
—
EPSS
0.2%
Published
Dec 9, 2025
CISA due date
—
Cloudanix analysis
A bug in the Linux storage software could cause warning messages or minor instability when RAID disks are added and removed at the same time.
- Exploitation
- Local Privilege
- Attacker needs
- Low Privilege
- Complexity
- Moderate
- Impact
- Other
- Component
- OS kernel
- Class
- Race Condition
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
Race condition in Linux kernel MD driver causes holder mismatch between blkdev_get_by_dev and blkdev_put when mddev->external transitions from 0 to 1, resulting in incorrect reference tracking and kernel warnings during rdev export.
Why it matters to the business
Storage arrays using MD RAID may experience unexpected warnings or instability during dynamic device add/remove operations, increasing operational risk in environments with frequent RAID reconfiguration.
How an attack unfolds
A local attacker triggers concurrent sysfs operations to add and remove devices while toggling the external flag on an MD array, causing the holder mismatch path to execute and surface the warning; no remote vector or privilege escalation is involved.
How to fix it
Upgrade the Linux kernel to commit 99fcd427178d0f58f5520f8f01df727f8eaeb2c7 or later; apply the vendor-supplied package update that includes the corrected holder tracking logic in export_rdev.
How to confirm the fix worked
Confirm kernel version contains the fix commit; reproduce the 23rdev-lifetime test case and verify absence of the blkdev_put warning; inspect block/bdev.c for proper holder recording on external flag change.
Typical attack path
- Obtain local shell access on a system using the Linux MD driver
- Create or select an MD array and set external flag via sysfs
- Concurrently invoke add_by_sysfs and remove_by_sysfs loops
- Trigger mddev_unlock and export_rdev to hit the mismatched holder path
How to detect it
Search kernel logs for WARNING messages originating from blkdev_put during md_mod operations; review sysfs activity on /sys/block/md*/md/ for concurrent new_dev and state remove patterns around the time of the warning.
What your security team should do
- Prioritize kernel updates on systems exposing MD sysfs interfaces to untrusted local users
- Monitor for the blkdev_put warning in dmesg on RAID hosts
- Restrict local access to md sysfs paths until patched
The record
In the Linux kernel, the following vulnerability has been resolved: md: fix warning for holder mismatch from export_rdev() Commit a1d767191096 ("md: use mddev->external to select holder in export_rdev()") fix the problem that 'claim_rdev' is used for blkdev_get_by_dev() while 'rdev' is used for blkdev_put(). However, if mddev->external is changed from 0 to 1, then 'rdev' is used for blkdev_get_by_dev() while 'claim_rdev' is used for blkdev_put(). And this problem can be reporduced reliably by following: New file: mdadm/tests/23rdev-lifetime devname=${dev0##*/} devt=`cat /sys/block/$devname/dev` pid="" runtime=2 clean_up_test() { pill -9 $pid echo clear > /sys/block/md0/md/array_state } trap 'clean_up_test' EXIT add_by_sysfs() { while true; do echo $devt > /sys/block/md0/md/new_dev done } remove_by_sysfs(){ while true; do echo remove > /sys/block/md0/md/dev-${devname}/state done } echo md0 > /sys/module/md_mod/parameters/new_array || die "create md0 failed" add_by_sysfs & pid="$pid $!" remove_by_sysfs & pid="$pid $!" sleep $runtime exit 0 Test cmd: ./test --save-logs --logdir=/tmp/ --keep-going --dev=loop --tests=23rdev-lifetime Test result: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 960 at block/bdev.c:618 blkdev_put+0x27c/0x330 Modules linked in: multipath md_mod loop CPU: 0 PID: 960 Comm: test Not tainted 6.5.0-rc2-00121-g01e55c376936-dirty #50 RIP: 0010:blkdev_put+0x27c/0x330 Call Trace: <TASK> export_rdev.isra.23+0x50/0xa0 [md_mod] mddev_unlock+0x19d/0x300 [md_mod] rdev_attr_store+0xec/0x190 [md_mod] sysfs_kf_write+0x52/0x70 kernfs_fop_write_iter+0x19a/0x2a0 vfs_write+0x3b5/0x770 ksys_write+0x74/0x150 __x64_sys_write+0x22/0x30 do_syscall_64+0x40/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Fix the problem by recording if 'rdev' is used as holder.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 6.5.0 | 6.5.5 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6_Update_19 | 0 | 1-150600.13.3.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-64kb | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-zfcpdump | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | dtb-aarch64 | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-64kb | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-debug | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| openSUSE:Leap 15.6 | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-kvmsmall | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-obs-qa | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.84.1 |
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