Strix
74.1K

CVE-2026-99256

Unknown

Last modified

CVE-2026-99256 is a vulnerability of currently unknown severity. In the Linux kernel, the following vulnerability has been resolved: dm cache: fix issue with background work locking dm cache used a rw_semaphore for background_work_lock. Write locks on rw_semaphores have strict owner semantics, but there was no guarantee that the process that locked background_work_lock was the same process that unlocked it.

Description

In the Linux kernel, the following vulnerability has been resolved: dm cache: fix issue with background work locking dm cache used a rw_semaphore for background_work_lock. Write locks on rw_semaphores have strict owner semantics, but there was no guarantee that the process that locked background_work_lock was the same process that unlocked it. This can be easily seen using a kernel compiled with CONFIG_DEBUG_RWSEMS. Given a dm cache device <cache>, run: 'dmsetup suspend <cache> && dmsetup resume <cache>'. This will trigger a kernel warning: DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)) triggered by cache_resume(). To fix this, switch from a rw_semaphore to a spinlock and a wait queue. dm cache already has a wait queue and associated counter, migration_wait and nr_allocated_migrations, that was getting woken up when background work was getting completed, but wasn't actually used by anything. This is replaced by the background_work queue and counter.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= b29d4986d0da1a27cd35917cdb433672f5c95d7f, < 0c7a8cad7c96012a9157a189649e569d0390f384; >= b29d4986d0da1a27cd35917cdb433672f5c95d7f, < f5db935d257023c3ef410bd39163b949b0e5a55d; >= b29d4986d0da1a27cd35917cdb433672f5c95d7f, < 6290507ecc0dd6dd40759729cbbbd49b1d2a63c4; >= b29d4986d0da1a27cd35917cdb433672f5c95d7f, < 8433fd005c25fd127021f67c9144a879fb585572; >= b29d4986d0da1a27cd35917cdb433672f5c95d7f, < 2f2cfa16dd0f4179bb988139dd37d00a42324f6c; >= b29d4986d0da1a27cd35917cdb433672f5c95d7f, < 73df2ff409f3db95029982fe3656329568e3715d; >= b29d4986d0da1a27cd35917cdb433672f5c95d7f, < 104f09e02038b0fc6bbb718b3976af029e15c1d0; >= b29d4986d0da1a27cd35917cdb433672f5c95d7f, < bc9781c0247de107876f32929f1637db93a42b34
LinuxLinux4.12

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-99256?
In the Linux kernel, the following vulnerability has been resolved: dm cache: fix issue with background work locking dm cache used a rw_semaphore for background_work_lock. Write locks on rw_semaphores have strict owner semantics, but there was no guarantee that the process that locked background_work_lock was the same process that unlocked it. This can be easily seen using a kernel compiled with CONFIG_DEBUG_RWSEMS. Given a dm cache device <cache>, run: 'dmsetup suspend <cache> && dmsetup resume <cache>'. This will trigger a kernel warning: DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)) triggered by cache_resume(). To fix this, switch from a rw_semaphore to a spinlock and a wait queue. dm cache already has a wait queue and associated counter, migration_wait and nr_allocated_migrations, that was getting woken up when background work was getting completed, but wasn't actually used by anything. This is replaced by the background_work queue and counter.
How severe is CVE-2026-99256?
Severity scoring for CVE-2026-99256 is pending analysis.
How do I fix CVE-2026-99256?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

Related CVEs from 2026

View all 2026CVEs →

Are you affected by CVE-2026-99256?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST