[tip: timers/urgent] hrtimer: Prevent queuing of hrtimer without a function callback

[tip-bot2 for Phil Chang]

The following commit has been merged into the timers/urgent branch of tip:

Commit-ID:     5a830bbce3af16833fe0092dec47b6dd30279825
Gitweb:        https://git.kernel.org/tip/5a830bbce3af16833fe0092dec47b6dd30279825
Author:        Phil Chang <phil.chang@xxxxxxxxxxxx>
AuthorDate:    Mon, 10 Jun 2024 21:31:36 +08:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 25 Jun 2024 16:54:27 +02:00

hrtimer: Prevent queuing of hrtimer without a function callback

The hrtimer function callback must not be NULL. It has to be specified by
the call side but it is not validated by the hrtimer code. When a hrtimer
is queued without a function callback, the kernel crashes with a null
pointer dereference when trying to execute the callback in __run_hrtimer().

Introduce a validation before queuing the hrtimer in
hrtimer_start_range_ns().

[anna-maria: Rephrase commit message]

Signed-off-by: Phil Chang <phil.chang@xxxxxxxxxxxx>
Signed-off-by: Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
---
 kernel/time/hrtimer.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 492c14a..b8ee320 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1285,6 +1285,8 @@ void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 	struct hrtimer_clock_base *base;
 	unsigned long flags;
 
+	if (WARN_ON_ONCE(!timer->function))
+		return;
 	/*
 	 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
 	 * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard