title: can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock
description: In the Linux kernel, the following vulnerability has been resolved:
can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock
The following 3 locks would race against each other, causing the
deadlock situation in the Syzbot bug report:
- j1939_socks_lock
- active_session_list_lock
- sk_session_queue_lock
A reasonable fix is to change j1939_socks_lock to an rwlock, since in
the rare situations where a write lock is required for the linked list
that j1939_socks_lock is protecting, the code does not attempt to
acquire any more locks. This would break the circular lock dependency,
where, for example, the current thread already locks j1939_socks_lock
and attempts to acquire sk_session_queue_lock, and at the same time,
another thread attempts to acquire j1939_socks_lock while holding
sk_session_queue_lock.
NOTE: This patch along does not fix the unregister_netdevice bug
reported by Syzbot; instead, it solves a deadlock situation to prepare
for one or more further patches to actually fix the Syzbot bug, which
appears to be a reference counting problem within the j1939 codebase.
[mkl: remove unrelated newline change]
affected:
{
product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 1da177e4c3f4, lessThan: 03358aba9916, status: affected, versionType: git
version: 1da177e4c3f4, lessThan: aedda066d717, status: affected, versionType: git
version: 1da177e4c3f4, lessThan: 26dfe112ec2e, status: affected, versionType: git
version: 1da177e4c3f4, lessThan: 559b6322f948, status: affected, versionType: git
version: 1da177e4c3f4, lessThan: 6cdedc18ba7b, status: affected, versionType: git
}
{
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 5.15.149, lessThanOrEqual: 5.15.*, status: unaffected, versionType: custom
version: 6.1.79, lessThanOrEqual: 6.1.*, status: unaffected, versionType: custom
version: 6.6.18, lessThanOrEqual: 6.6.*, status: unaffected, versionType: custom
version: 6.7.6, lessThanOrEqual: 6.7.*, status: unaffected, versionType: custom
version: 6.8, lessThanOrEqual: *, status: unaffected, versionType: original_commit_for_fix
}
