CVE-2026-23195

The record

In the Linux kernel, the following vulnerability has been resolved: cgroup/dmem: avoid pool UAF An UAF issue was observed: BUG: KASAN: slab-use-after-free in page_counter_uncharge+0x65/0x150 Write of size 8 at addr ffff888106715440 by task insmod/527 CPU: 4 UID: 0 PID: 527 Comm: insmod 6.19.0-rc7-next-20260129+ #11 Tainted: [O]=OOT_MODULE Call Trace: <TASK> dump_stack_lvl+0x82/0xd0 kasan_report+0xca/0x100 kasan_check_range+0x39/0x1c0 page_counter_uncharge+0x65/0x150 dmem_cgroup_uncharge+0x1f/0x260 Allocated by task 527: Freed by task 0: The buggy address belongs to the object at ffff888106715400 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 64 bytes inside of freed 512-byte region [ffff888106715400, ffff888106715600) The buggy address belongs to the physical page: Memory state around the buggy address: ffff888106715300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888106715380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888106715400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888106715480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888106715500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb The issue occurs because a pool can still be held by a caller after its associated memory region is unregistered. The current implementation frees the pool even if users still hold references to it (e.g., before uncharge operations complete). This patch adds a reference counter to each pool, ensuring that a pool is only freed when its reference count drops to zero.

Affected packages

Related vulnerabilities

• CVE-2026-23226 In the Linux kernel, the following vulnerability has been resolved: ksmbd: add chann_lock… Also affects Kernel
• CVE-2026-23225 In the Linux kernel, the following vulnerability has been resolved: sched/mmcid: Don't… Also affects Kernel
• CVE-2026-23230 In the Linux kernel, the following vulnerability has been resolved: smb: client: split… Also affects Kernel
• CVE-2026-23224 In the Linux kernel, the following vulnerability has been resolved: erofs: fix UAF issue… Also affects Kernel
• CVE-2026-23227 In the Linux kernel, the following vulnerability has been resolved: drm/exynos: vidi: use… Also affects Kernel
• CVE-2026-23223 In the Linux kernel, the following vulnerability has been resolved: xfs: fix UAF in… Also affects Kernel
• CVE-2026-23228 In the Linux kernel, the following vulnerability has been resolved: smb: server: fix leak… Also affects Kernel
• CVE-2026-23229 In the Linux kernel, the following vulnerability has been resolved: crypto: virtio - Add… Also affects Kernel