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panic: Introduce warn_limit

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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: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221117234328.594699-5-keescook@chromium.org
This commit is contained in:
Kees Cook 2022-11-17 15:43:25 -08:00
parent 79cc1ba7ba
commit 9fc9e278a5
2 changed files with 24 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

10
Documentation/admin-guide/sysctl/kernel.rst
View file

@ -1509,6 +1509,16 @@ entry will default to 2 instead of 0.
2 Unprivileged calls to ``bpf()`` are disabled 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 watchdog
======== ========

14
kernel/panic.c
View file

@ -58,6 +58,7 @@ bool crash_kexec_post_notifiers;
int panic_on_warn __read_mostly; int panic_on_warn __read_mostly;
unsigned long panic_on_taint; unsigned long panic_on_taint;
bool panic_on_taint_nousertaint = false; bool panic_on_taint_nousertaint = false;
static unsigned int warn_limit __read_mostly;
int panic_timeout = CONFIG_PANIC_TIMEOUT; int panic_timeout = CONFIG_PANIC_TIMEOUT;
EXPORT_SYMBOL_GPL(panic_timeout); EXPORT_SYMBOL_GPL(panic_timeout);
@ -88,6 +89,13 @@ static struct ctl_table kern_panic_table[] = {
.extra2 = SYSCTL_ONE, .extra2 = SYSCTL_ONE,
}, },
#endif #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) void check_panic_on_warn(const char *origin)
{ {
static atomic_t warn_count = ATOMIC_INIT(0);
if (panic_on_warn) if (panic_on_warn)
panic("%s: panic_on_warn set ...\n", origin); 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);
} }
/** /**