PT-2026-44282 · Linux · Linux

Published 2026-05-28 · Updated 2026-05-28 · CVE-2026-46159

NVD

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.

Related Identifiers

CVE-2026-46159

Affected Products

Linux

References · 6

• https://nvd.nist.gov/vuln/detail/CVE-2026-46159 · Security Note
• https://git.kernel.org/stable/c/973e57c726c1f8e77259d1c8e519519f1e9aea77 · Note
• https://git.kernel.org/stable/c/f5ee467b56764964027c361641f64953fc0f8f9a · Note
• https://git.kernel.org/stable/c/d09d67d5de577cedae3de9497dff217e0ac8b641 · Note
• https://git.kernel.org/stable/c/4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3 · Note
• https://git.kernel.org/stable/c/5d12e0ab009ade48c1bff9324fd9bea2c773d088 · Note