Commit e30a0361 authored by Jared Kangas's avatar Jared Kangas Committed by Andrew Morton
Browse files

kasan: make report_lock a raw spinlock 

If PREEMPT_RT is enabled, report_lock is a sleeping spinlock and must not
be locked when IRQs are disabled.  However, KASAN reports may be triggered
in such contexts.  For example:

        char *s = kzalloc(1, GFP_KERNEL);
        kfree(s);
        local_irq_disable();
        char c = *s;  /* KASAN report here leads to spin_lock() */
        local_irq_enable();

Make report_spinlock a raw spinlock to prevent rescheduling when
PREEMPT_RT is enabled.

Link: https://lkml.kernel.org/r/20241119210234.1602529-1-jkangas@redhat.com


Fixes: 342a9324 ("locking/spinlock: Provide RT variant header: <linux/spinlock_rt.h>")
Signed-off-by: default avatarJared Kangas <jkangas@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 091c1dd2

mm/kasan/report.c

+3 −3
Original line number Diff line number Diff line
@@ -201,7 +201,7 @@ static inline void fail_non_kasan_kunit_test(void) { } 


#endif /* CONFIG_KUNIT */



static DEFINE_SPINLOCK(report_lock);

static DEFINE_RAW_SPINLOCK(report_lock);



static void start_report(unsigned long *flags, bool sync)

{
@@ -212,7 +212,7 @@ static void start_report(unsigned long *flags, bool sync) 
	lockdep_off();

	/* Make sure we don't end up in loop. */

	report_suppress_start();

	spin_lock_irqsave(&report_lock, *flags);

	raw_spin_lock_irqsave(&report_lock, *flags);

	pr_err("==================================================================\n");

}
@@ -222,7 +222,7 @@ static void end_report(unsigned long *flags, const void *addr, bool is_write) 
		trace_error_report_end(ERROR_DETECTOR_KASAN,

				       (unsigned long)addr);

	pr_err("==================================================================\n");

	spin_unlock_irqrestore(&report_lock, *flags);

	raw_spin_unlock_irqrestore(&report_lock, *flags);

	if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))

		check_panic_on_warn("KASAN");

	switch (kasan_arg_fault) {