In the Linux kernel, the following vulnerability has been resolved:tmpfs: fix race on handling dquot rbtreeA 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 2shmem_release_dquot()			- shmem_{acquire,release}_dquot()fetch ROOT				- Fetch ROOTwait dqio_semacquire dqio_semstart searching for the node, but
from the wrong location, missing
the node, and triggering a warning.