Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-05-28T00:00:00 kernel: btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CWE-367

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak btrfs_ioctl_space_info() has a TOCTOU race between two passes over the block group RAID type lists. The first pass counts entries to determine the allocation size, then the second pass fills the buffer. The groups_sem rwlock is released between passes, allowing concurrent block group removal to reduce the entry count. When the second pass fills fewer entries than the first pass counted, copy_to_user() copies the full alloc_size bytes including trailing uninitialized kmalloc bytes to userspace. Fix by copying only total_spaces entries (the actually-filled count from the second pass) instead of alloc_size bytes, and switch to kzalloc so any future copy size mismatch cannot leak heap data.

A flaw was found in the btrfs filesystem within the Linux kernel. A Time-of-check to time-of-use (TOCTOU) race condition in the `btrfs_ioctl_space_info()` function allows a local attacker to exploit a timing window. This occurs when the system counts entries for allocation size and then fills a buffer, but a concurrent operation reduces the entry count between these two steps. Consequently, uninitialized kernel memory may be copied to userspace, leading to information disclosure.

Red Hat Enterprise Linux 10 Fix deferred kernel Red Hat Enterprise Linux 6 Out of support scope kernel Red Hat Enterprise Linux 7 Fix deferred kernel Red Hat Enterprise Linux 7 Fix deferred kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Not affected kernel Red Hat Enterprise Linux 9 Not affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-46159 https://nvd.nist.gov/vuln/detail/CVE-2026-46159 https://lore.kernel.org/linux-cve-announce/2026052824-CVE-2026-46159-2689@gregkh/T