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); } /**
