In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel
The following race is possible between bpf_timer_cancel_and_free
and bpf_timer_cancel. It will lead a UAF on the timer->timer.
bpf_timer_cancel();
spin_lock();
t = timer->time;
spin_unlock();
bpf_timer_cancel_and_free();
spin_lock();
t = timer->timer;
timer->timer = NULL;
spin_unlock();
hrtimer_cancel(&t->timer);
kfree(t);
/* UAF on t */
hrtimer_cancel(&t->timer);
In bpf_timer_cancel_and_free, this patch frees the timer->timer
after a rcu grace period. This requires a rcu_head addition
to the "struct bpf_hrtimer". Another kfree(t) happens in bpf_timer_init,
this does not need a kfree_rcu because it is still under the
spin_lock and timer->timer has not been visible by others yet.
In bpf_timer_cancel, rcu_read_lock() is added because this helper
can be used in a non rcu critical section context (e.g. from
a sleepable bpf prog). Other timer->timer usages in helpers.c
have been audited, bpf_timer_cancel() is the only place where
timer->timer is used outside of the spin_lock.
Another solution considered is to mark a t->flag in bpf_timer_cancel
and clear it after hrtimer_cancel() is done. In bpf_timer_cancel_and_free,
it busy waits for the flag to be cleared before kfree(t). This patch
goes with a straight forward solution and frees timer->timer after
a rcu grace period.
Metrics
Affected Vendors & Products
References
History
Wed, 07 Aug 2024 22:45:00 +0000
Type | Values Removed | Values Added |
---|---|---|
CPEs | cpe:/a:redhat:rhel_eus:9.2 |
Wed, 07 Aug 2024 10:45:00 +0000
Type | Values Removed | Values Added |
---|---|---|
First Time appeared |
Redhat rhel Eus
|
|
CPEs | cpe:/a:redhat:rhel_eus:9.2::nfv | |
Vendors & Products |
Redhat rhel Eus
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published: 2024-04-03T17:00:23.414Z
Updated: 2024-11-05T09:14:48.949Z
Reserved: 2024-02-19T14:20:24.166Z
Link: CVE-2024-26737
Vulnrichment
Updated: 2024-08-02T00:14:13.230Z
NVD
Status : Awaiting Analysis
Published: 2024-04-03T17:15:51.243
Modified: 2024-11-21T09:02:57.210
Link: CVE-2024-26737
Redhat