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Date: Wed, 1 Feb 2023 20:42:52 -0800
From: Eric Biggers <ebiggers@...nel.org>
To: stable@...r.kernel.org
Cc: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>,
Kees Cook <keescook@...omium.org>,
SeongJae Park <sj@...nel.org>,
Seth Jenkins <sethjenkins@...gle.com>,
Jann Horn <jannh@...gle.com>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
Jonathan Corbet <corbet@....net>,
Andrew Morton <akpm@...ux-foundation.org>,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
"Jason A. Donenfeld" <Jason@...c4.com>,
Eric Biggers <ebiggers@...gle.com>,
Huang Ying <ying.huang@...el.com>,
Petr Mladek <pmladek@...e.com>,
tangmeng <tangmeng@...ontech.com>,
"Guilherme G. Piccoli" <gpiccoli@...lia.com>,
Tiezhu Yang <yangtiezhu@...ngson.cn>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
linux-doc@...r.kernel.org, Luis Chamberlain <mcgrof@...nel.org>
Subject: [PATCH 5.4 14/17] panic: Introduce warn_limit
From: Kees Cook <keescook@...omium.org>
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@....net>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Eric Biggers <ebiggers@...gle.com>
Cc: Huang Ying <ying.huang@...el.com>
Cc: Petr Mladek <pmladek@...e.com>
Cc: tangmeng <tangmeng@...ontech.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc: Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: linux-doc@...r.kernel.org
Reviewed-by: Luis Chamberlain <mcgrof@...nel.org>
Signed-off-by: Kees Cook <keescook@...omium.org>
Link: https://lore.kernel.org/r/20221117234328.594699-5-keescook@chromium.org
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
Documentation/admin-guide/sysctl/kernel.rst | 10 ++++++++
kernel/panic.c | 27 +++++++++++++++++++++
2 files changed, 37 insertions(+)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index bc31c4a88f20f..568c24ff00a72 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1186,6 +1186,16 @@ entry will default to 2 instead of 0.
2 Unprivileged calls to ``bpf()`` are disabled
= =============================================================
+
+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:
=========
diff --git a/kernel/panic.c b/kernel/panic.c
index 7e4900eb25ac1..8f72305dd501d 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -44,6 +44,7 @@ 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);
@@ -60,6 +61,26 @@ 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;
@@ -158,8 +179,14 @@ static void panic_print_sys_info(void)
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);
}
/**
--
2.39.1
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