In the Linux kernel, the following vulnerability has been resolved: exec: do_close_on_exec() before taking exec_update_lock do_close_on_exec() currently happens while holding the exec_update_lock, which is used in a lot of places that …

Overview

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

exec: do_close_on_exec() before taking exec_update_lock

do_close_on_exec() currently happens while holding the exec_update_lock, which is used in a lot of places that access process state to synchronize access checks. I recently added another such use of exec_update_lock, causing a regression.

do_close_on_exec() can block waiting for a reply from a filesystem. That means a hung filesystem can block codepaths that use exec_update_lock; and it also means that a FUSE filesystem which attempts to inspect the calling process can deadlock.

To avoid such problems, move do_close_on_exec() before the exec_update_lock is taken, but after the FD table has been copied if necessary.

I have looked through all the calls between the old and new position of the do_close_on_exec() call; there seems to be no file descriptor table access in between.

Remediation

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