This is a note to let you know that I've just added the patch titled
panic: Introduce warn_limit
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
panic-introduce-warn_limit.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9fc9e278a5c0b708eeffaf47d6eb0c82aa74ed78 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@xxxxxxxxxxxx>
Date: Thu, 17 Nov 2022 15:43:25 -0800
Subject: panic: Introduce warn_limit
From: Kees Cook <keescook@xxxxxxxxxxxx>
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@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: "Jason A. Donenfeld" <Jason@xxxxxxxxx>
Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: tangmeng <tangmeng@xxxxxxxxxxxxx>
Cc: "Guilherme G. Piccoli" <gpiccoli@xxxxxxxxxx>
Cc: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: linux-doc@xxxxxxxxxxxxxxx
Reviewed-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20221117234328.594699-5-keescook@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/sysctl/kernel.rst | 10 ++++++++++
kernel/panic.c | 14 ++++++++++++++
2 files changed, 24 insertions(+)
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1532,6 +1532,16 @@ 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
========
--- 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;
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 co
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);
}
/**
Patches currently in stable-queue which might be from keescook@xxxxxxxxxxxx are
queue-6.1/panic-consolidate-open-coded-panic_on_warn-checks.patch
queue-6.1/exit-put-an-upper-limit-on-how-often-we-can-oops.patch
queue-6.1/panic-introduce-warn_limit.patch
queue-6.1/exit-allow-oops_limit-to-be-disabled.patch
queue-6.1/panic-separate-sysctl-logic-from-config_smp.patch
queue-6.1/exit-use-read_once-for-all-oops-warn-limit-reads.patch
queue-6.1/exit-expose-oops_count-to-sysfs.patch
queue-6.1/panic-expose-warn_count-to-sysfs.patch
queue-6.1/docs-fix-path-paste-o-for-sys-kernel-warn_count.patch
