6.6-stable review patch. If anyone has any objections, please let me know.
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From: Jared Kangas jkangas@redhat.com
commit e30a0361b8515d424c73c67de1a43e45a13b8ba2 upstream.
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: 342a93247e08 ("locking/spinlock: Provide RT variant header: <linux/spinlock_rt.h>") Signed-off-by: Jared 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: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/kasan/report.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -199,7 +199,7 @@ 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) { @@ -210,7 +210,7 @@ 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"); }
@@ -220,7 +220,7 @@ 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) {