The patch titled
Subject: kasan: make report_lock a raw spinlock
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
kasan-make-report_lock-a-raw-spinlock.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kasan-make-report_lock-a-raw-spinlock.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Jared Kangas <jkangas@xxxxxxxxxx>
Subject: kasan: make report_lock a raw spinlock
Date: Tue, 19 Nov 2024 13:02:34 -0800
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@xxxxxxxxxx
Signed-off-by: Jared Kangas <jkangas@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kasan/report.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/mm/kasan/report.c~kasan-make-report_lock-a-raw-spinlock
+++ a/mm/kasan/report.c
@@ -200,7 +200,7 @@ static inline void fail_non_kasan_kunit_
#endif /* CONFIG_KUNIT */
-static DEFINE_SPINLOCK(report_lock);
+static DEFINE_RAW_SPINLOCK(report_lock);
static void start_report(unsigned long *flags, bool sync)
{
@@ -211,7 +211,7 @@ static void start_report(unsigned long *
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");
}
@@ -221,7 +221,7 @@ static void end_report(unsigned long *fl
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) {
_
Patches currently in -mm which might be from jkangas@xxxxxxxxxx are
kasan-make-report_lock-a-raw-spinlock.patch
