CVE-2024-27058

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

tmpfs: fix race on handling dquot rbtree

A syzkaller reproducer found a race while attempting to remove dquot
information from the rb tree.

Fetching the rb_tree root node must also be protected by the
dqopt->dqio_sem, otherwise, giving the right timing, shmem_release_dquot()
will trigger a warning because it couldn’t find a node in the tree, when
the real reason was the root node changing before the search starts:

Thread 1 Thread 2
– shmem_release_dquot() – shmem_{acquire,release}_dquot()

– fetch ROOT – Fetch ROOT

– acquire dqio_sem
– wait dqio_sem

– do something, triger a tree rebalance
– release dqio_sem

– acquire dqio_sem
– start searching for the node, but
from the wrong location, missing
the node, and triggering a warning.

More information : https://git.kernel.org/stable/c/0a69b6b3a026543bc215ccc866d0aea5579e6ce2