Re: [PATCH v3 4/6] panic: Consolidate open-coded panic_on_warn checks

From: Marco Elver
Date: Fri Nov 18 2022 - 03:35:19 EST

On Fri, 18 Nov 2022 at 00:43, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll
> their own warnings, and each check "panic_on_warn". Consolidate this
> into a single function so that future instrumentation can be added in
> a single location.
>
> Cc: Marco Elver <elver@xxxxxxxxxx>
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
> Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
> Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Ben Segall <bsegall@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
> Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
> Cc: Alexander Potapenko <glider@xxxxxxxxxx>
> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: David Gow <davidgow@xxxxxxxxxx>
> Cc: tangmeng <tangmeng@xxxxxxxxxxxxx>
> Cc: Jann Horn <jannh@xxxxxxxxxx>
> Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
> Cc: Petr Mladek <pmladek@xxxxxxxx>
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Cc: "Guilherme G. Piccoli" <gpiccoli@xxxxxxxxxx>
> Cc: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> Cc: kasan-dev@xxxxxxxxxxxxxxxx
> Cc: linux-mm@xxxxxxxxx
> Reviewed-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

Reviewed-by: Marco Elver <elver@xxxxxxxxxx>

> ---
> include/linux/panic.h | 1 +
> kernel/kcsan/report.c | 3 +--
> kernel/panic.c | 9 +++++++--
> kernel/sched/core.c | 3 +--
> lib/ubsan.c | 3 +--
> mm/kasan/report.c | 4 ++--
> mm/kfence/report.c | 3 +--
> 7 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/panic.h b/include/linux/panic.h
> index c7759b3f2045..979b776e3bcb 100644
> --- a/include/linux/panic.h
> +++ b/include/linux/panic.h
> @@ -11,6 +11,7 @@ extern long (*panic_blink)(int state);
> __printf(1, 2)
> void panic(const char *fmt, ...) __noreturn __cold;
> void nmi_panic(struct pt_regs *regs, const char *msg);
> +void check_panic_on_warn(const char *origin);
> extern void oops_enter(void);
> extern void oops_exit(void);
> extern bool oops_may_print(void);
> diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
> index 67794404042a..e95ce7d7a76e 100644
> --- a/kernel/kcsan/report.c
> +++ b/kernel/kcsan/report.c
> @@ -492,8 +492,7 @@ static void print_report(enum kcsan_value_change value_change,
> dump_stack_print_info(KERN_DEFAULT);
> pr_err("==================================================================\n");
>
> - if (panic_on_warn)
> - panic("panic_on_warn set ...\n");
> + check_panic_on_warn("KCSAN");
> }
>
> static void release_report(unsigned long *flags, struct other_info *other_info)
> diff --git a/kernel/panic.c b/kernel/panic.c
> index d843d036651e..cfa354322d5f 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -201,6 +201,12 @@ static void panic_print_sys_info(bool console_flush)
> ftrace_dump(DUMP_ALL);
> }
>
> +void check_panic_on_warn(const char *origin)
> +{
> + if (panic_on_warn)
> + panic("%s: panic_on_warn set ...\n", origin);
> +}
> +
> /**
> * panic - halt the system
> * @fmt: The text string to print
> @@ -619,8 +625,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
> if (regs)
> show_regs(regs);
>
> - if (panic_on_warn)
> - panic("panic_on_warn set ...\n");
> + check_panic_on_warn("kernel");
>
> if (!regs)
> dump_stack();
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 5800b0623ff3..285ef8821b4f 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5729,8 +5729,7 @@ static noinline void __schedule_bug(struct task_struct *prev)
> pr_err("Preemption disabled at:");
> print_ip_sym(KERN_ERR, preempt_disable_ip);
> }
> - if (panic_on_warn)
> - panic("scheduling while atomic\n");
> + check_panic_on_warn("scheduling while atomic");
>
> dump_stack();
> add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
> diff --git a/lib/ubsan.c b/lib/ubsan.c
> index 36bd75e33426..60c7099857a0 100644
> --- a/lib/ubsan.c
> +++ b/lib/ubsan.c
> @@ -154,8 +154,7 @@ static void ubsan_epilogue(void)
>
> current->in_ubsan--;
>
> - if (panic_on_warn)
> - panic("panic_on_warn set ...\n");
> + check_panic_on_warn("UBSAN");
> }
>
> void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index df3602062bfd..cc98dfdd3ed2 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -164,8 +164,8 @@ static void end_report(unsigned long *flags, void *addr)
> (unsigned long)addr);
> pr_err("==================================================================\n");
> spin_unlock_irqrestore(&report_lock, *flags);
> - if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
> - panic("panic_on_warn set ...\n");
> + if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
> + check_panic_on_warn("KASAN");
> if (kasan_arg_fault == KASAN_ARG_FAULT_PANIC)
> panic("kasan.fault=panic set ...\n");
> add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
> diff --git a/mm/kfence/report.c b/mm/kfence/report.c
> index 7e496856c2eb..110c27ca597d 100644
> --- a/mm/kfence/report.c
> +++ b/mm/kfence/report.c
> @@ -268,8 +268,7 @@ void kfence_report_error(unsigned long address, bool is_write, struct pt_regs *r
>
> lockdep_on();
>
> - if (panic_on_warn)
> - panic("panic_on_warn set ...\n");
> + check_panic_on_warn("KFENCE");
>
> /* We encountered a memory safety error, taint the kernel! */
> add_taint(TAINT_BAD_PAGE, LOCKDEP_STILL_OK);
> --
> 2.34.1
>