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Message-Id: <20221117234328.594699-5-keescook@chromium.org>
Date: Thu, 17 Nov 2022 15:43:25 -0800
From: Kees Cook <keescook@...omium.org>
To: Jann Horn <jannh@...gle.com>
Cc: Kees Cook <keescook@...omium.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>,
Seth Jenkins <sethjenkins@...gle.com>,
Greg KH <gregkh@...uxfoundation.org>,
Linus Torvalds <torvalds@...uxfoundation.org>,
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Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
Laurent Dufour <ldufour@...ux.ibm.com>,
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Subject: [PATCH v3 5/6] panic: Introduce warn_limit
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>
---
Documentation/admin-guide/sysctl/kernel.rst | 9 +++++++++
kernel/panic.c | 14 ++++++++++++++
2 files changed, 23 insertions(+)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 09f3fb2f8585..c385d5319cdf 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1508,6 +1508,15 @@ 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 or 1 has the same effect
+as setting ``panic_on_warn=1``.
+
+
watchdog
========
diff --git a/kernel/panic.c b/kernel/panic.c
index cfa354322d5f..e5aab27496d7 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -58,6 +58,7 @@ bool crash_kexec_post_notifiers;
int panic_on_warn __read_mostly;
unsigned long panic_on_taint;
bool panic_on_taint_nousertaint = false;
+static unsigned int warn_limit __read_mostly = 10000;
int panic_timeout = CONFIG_PANIC_TIMEOUT;
EXPORT_SYMBOL_GPL(panic_timeout);
@@ -88,6 +89,13 @@ static struct ctl_table kern_panic_table[] = {
.extra2 = SYSCTL_ONE,
},
#endif
+ {
+ .procname = "warn_limit",
+ .data = &warn_limit,
+ .maxlen = sizeof(warn_limit),
+ .mode = 0644,
+ .proc_handler = proc_douintvec,
+ },
{ }
};
@@ -203,8 +211,14 @@ static void panic_print_sys_info(bool console_flush)
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))
+ panic("%s: system warned too often (kernel.warn_limit is %d)",
+ warn_limit);
}
/**
--
2.34.1
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