autofs: fix sbi->pipe file reference leak in autofs_kill_sb()

Overview

In the Linux kernel, the following vulnerability has been resolved:

autofs: fix sbi->pipe file reference leak in autofs_kill_sb()

When autofs_fill_super() fails before clearing AUTOFS_SBI_CATATONIC (for example, when find_get_pid() fails on an invalid pgrp mount option, or when an fs_context is closed before mounting), deactivate_locked_super() invokes autofs_kill_sb() -> autofs_catatonic_mode(sbi).

Because AUTOFS_SBI_CATATONIC is still set in sbi->flags, autofs_catatonic_mode() returns early without calling fput(sbi->pipe), permanently leaking the pipe struct file reference.

Explicitly release sbi->pipe in autofs_kill_sb() if it is still non-NULL after autofs_catatonic_mode().

Affected

• Linux >= ebc921ca9b92a3cf304d99bd7b7f373ec78c7ed7 < 3684e2273ba94553af3c5195a46a50214a1a96e3
• Linux >= ebc921ca9b92a3cf304d99bd7b7f373ec78c7ed7 < 0662b1ff9b383d5a233d344e4dc518c27a17f7b8
• Linux >= ebc921ca9b92a3cf304d99bd7b7f373ec78c7ed7 < 34fa4c1c6e10507dc60e35a82cc9655666946cfd
• Linux >= ebc921ca9b92a3cf304d99bd7b7f373ec78c7ed7 < a58593b501b7be5ad2bc5181bfa8cd4599be257c
• Linux >= ebc921ca9b92a3cf304d99bd7b7f373ec78c7ed7 < f1c57f5b16bbc3571bd479c290996c4d4e1fb931
• Linux >= ebc921ca9b92a3cf304d99bd7b7f373ec78c7ed7 < 4bcb371019097d0e357f097902587401c509bbc9
• Linux >= ebc921ca9b92a3cf304d99bd7b7f373ec78c7ed7 < fc4fd0281ac80b5a3c5a2330f688f0f9d2a420b6
• Linux >= ebc921ca9b92a3cf304d99bd7b7f373ec78c7ed7 < aa5e44b29ffe4eaa08cc2237fd65bc2596bc023e
• Linux 4.18

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.