CVE-2024-26737
bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
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.
En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: bpf: Corrección de ejecucións entre bpf_timer_cancel_and_free y bpf_timer_cancel La siguiente ejecución es posible entre bpf_timer_cancel_and_free y bpf_timer_cancel. Dirigirá una UAF en el temporizador->temporizador. bpf_timer_cancel(); spin_lock(); t = temporizador->tiempo; spin_unlock(); bpf_timer_cancel_and_free(); spin_lock(); t = temporizador->temporizador; temporizador->temporizador = NULL; spin_unlock(); hrtimer_cancel(&t->temporizador); klibre(t); /* UAF en t */ hrtimer_cancel(&t->timer); En bpf_timer_cancel_and_free, este parche libera el temporizador->temporizador después de un período de gracia de rcu. Esto requiere una adición de rcu_head a "struct bpf_hrtimer". Otro kfree(t) ocurre en bpf_timer_init, esto no necesita un kfree_rcu porque todavía está bajo spin_lock y otros aún no han visible el temporizador->temporizador. En bpf_timer_cancel, se agrega rcu_read_lock() porque este asistente puede usarse en un contexto de sección no crítica para rcu (por ejemplo, desde un programa bpf que se puede dormir). Se han auditado otros usos de temporizador->temporizador en helpers.c, bpf_timer_cancel() es el único lugar donde se usa temporizador->temporizador fuera de spin_lock. Otra solución considerada es marcar una bandera t-> en bpf_timer_cancel y borrarla una vez finalizado hrtimer_cancel(). En bpf_timer_cancel_and_free, está ocupado esperando a que se borre la bandera antes de kfree(t). Este parche incluye una solución sencilla y libera el temporizador->temporizador después de un período de gracia de rcu.
A use-after-free flaw was found in the Linux kernel’s BPF functionality. This flaw allows a local user to crash the system.
CVSS Scores
SSVC
- Decision:Track
Timeline
- 2024-02-19 CVE Reserved
- 2024-04-03 CVE Published
- 2024-04-04 EPSS Updated
- 2024-08-02 CVE Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
- CWE-416: Use After Free
CAPEC
References (8)
| URL | Tag | Source |
|---|---|---|
| https://git.kernel.org/stable/c/b00628b1c7d595ae5b544e059c27b1f5828314b4 | Vuln. Introduced |
| URL | Date | SRC |
|---|
| URL | Date | SRC |
|---|---|---|
| https://access.redhat.com/security/cve/CVE-2024-26737 | 2024-08-07 | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2273274 | 2024-08-07 |
Affected Vendors, Products, and Versions
| Vendor | Product | Version | Other | Status | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.15 < 5.15.150 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.15 < 5.15.150" | en |
Affected
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| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.15 < 6.1.80 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.15 < 6.1.80" | en |
Affected
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| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.15 < 6.6.19 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.15 < 6.6.19" | en |
Affected
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| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.15 < 6.7.7 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.15 < 6.7.7" | en |
Affected
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| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.15 < 6.8 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.15 < 6.8" | en |
Affected
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