CVSS 7.8 · High EPSS 0,25%
Kerentanan Use After Free pada linux kernel. Skor CVSS 3.1 7.8 (High) menurut CNA.
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.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
· uraikan di kalkulator | Vendor | Produk | Versi terdampak |
|---|---|---|
| linux | linux kernel | Versi 5.15 hingga sebelum 5.15.150 |
| linux | linux kernel | Versi 5.16 hingga sebelum 6.1.80 |
| linux | linux kernel | Versi 6.2 hingga sebelum 6.6.19 |
| linux | linux kernel | Versi 6.7 hingga sebelum 6.7.7 |
| linux | linux kernel | Versi 6.8 rc1 |
| linux | linux kernel | Versi 6.8 rc2 |
| linux | linux kernel | Versi 6.8 rc3 |
| linux | linux kernel | Versi 6.8 rc4 |
| linux | linux kernel | Versi 6.8 rc5 |