On Wed, 9 Nov 2022 at 21:00, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > 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 > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > Documentation/admin-guide/sysctl/kernel.rst | 9 +++++++++ > kernel/panic.c | 13 +++++++++++++ > 2 files changed, 22 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 3afd234767bc..b235fa4a6fc8 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 +211,13 @@ static void panic_print_sys_info(bool console_flush) > > void check_panic_on_warn(const char *reason) > { > + static atomic_t warn_count = ATOMIC_INIT(0); > + > if (panic_on_warn) > panic("%s: panic_on_warn set ...\n", reason); > + > + if (atomic_inc_return(&warn_count) >= READ_ONCE(warn_limit)) > + panic("Warned too often (warn_limit is %d)", warn_limit); Shouldn't this also include the "reason", like above? (Presumably a warning had just been generated to console so the reason is easy enough to infer from the log, although in that case "reason" also seems redundant above.)