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Commit a40af7cd authored by Kees Cook's avatar Kees Cook Committed by Greg Kroah-Hartman
Browse files

panic: Introduce warn_limit 



commit 9fc9e278a5c0b708eeffaf47d6eb0c82aa74ed78 upstream.

Like oops_limit, add warn_limit for limiting the number of warnings when
panic_on_warn is not set.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: tangmeng <tangmeng@uniontech.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-doc@vger.kernel.org
Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221117234328.594699-5-keescook@chromium.org


Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent dcdce952

Documentation/sysctl/kernel.txt

+10 −0
Original line number Diff line number Diff line
@@ -97,6 +97,7 @@ show up in /proc/sys/kernel: 
- threads-max

- unprivileged_bpf_disabled

- unknown_nmi_panic

- warn_limit

- watchdog

- watchdog_thresh

- version
@@ -1114,6 +1115,15 @@ example. If a system hangs up, try pressing the NMI switch. 


==============================================================



warn_limit:



Number of kernel warnings after which the kernel should panic when

``panic_on_warn`` is not set. Setting this to 0 disables checking

the warning count. Setting this to 1 has the same effect as setting

``panic_on_warn=1``. The default value is 0.



==============================================================



watchdog:



This parameter can be used to disable or enable the soft lockup detector

kernel/panic.c

+27 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ static int pause_on_oops_flag; 
static DEFINE_SPINLOCK(pause_on_oops_lock);

bool crash_kexec_post_notifiers;

int panic_on_warn __read_mostly;

static unsigned int warn_limit __read_mostly;



int panic_timeout = CONFIG_PANIC_TIMEOUT;

EXPORT_SYMBOL_GPL(panic_timeout);
@@ -50,6 +51,26 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 


EXPORT_SYMBOL(panic_notifier_list);



#ifdef CONFIG_SYSCTL

static struct ctl_table kern_panic_table[] = {

	{

		.procname       = "warn_limit",

		.data           = &warn_limit,

		.maxlen         = sizeof(warn_limit),

		.mode           = 0644,

		.proc_handler   = proc_douintvec,

	},

	{ }

};



static __init int kernel_panic_sysctls_init(void)

{

	register_sysctl_init("kernel", kern_panic_table);

	return 0;

}

late_initcall(kernel_panic_sysctls_init);

#endif



static long no_blink(int state)

{

	return 0;
@@ -127,8 +148,14 @@ EXPORT_SYMBOL(nmi_panic); 


void check_panic_on_warn(const char *origin)

{

	static atomic_t warn_count = ATOMIC_INIT(0);



	if (panic_on_warn)

		panic("%s: panic_on_warn set ...\n", origin);



	if (atomic_inc_return(&warn_count) >= READ_ONCE(warn_limit) && warn_limit)

		panic("%s: system warned too often (kernel.warn_limit is %d)",

		      origin, warn_limit);

}



/**