From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 64E3226059D for ; Wed, 3 Dec 2025 18:02:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764784942; cv=none; b=BQGdLTRNbFGCEDootXYYn21BANpnA4NC0F1aydkP5ojdpq1DyaUKDbm43evftnqfe4pyYDq358YFzdZByQa0cML4daDABkmGFxfXLGM74JJCxoZ3nOs4eXHRzmWjsS6X75ZBfyCpmef/32iCf+KmPSwQ94yywxPFD14P+d/yIU8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764784942; c=relaxed/simple; bh=BvmAws+7BickkUuwVGpea4WpLtEaqudqsT7t/9G2GKw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aQi+49bBaSJ0TqNImCPRBqd/lXW+AWt9FOIrazGK17DDUTnX1LE5JI1QRbEulT8YpHOsgROf4O0zW5+MYiKf7TSMlYa2zeOcE7phhzIGYNROC4nTAbcLyGA5ImrsGU/YnEA3UvcnMWn2ySTtUX/11FNEDWaBaVuYVb7nVLRTF3g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=X33v0Y84; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="X33v0Y84" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8AB9C4CEF5; Wed, 3 Dec 2025 18:02:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764784942; bh=BvmAws+7BickkUuwVGpea4WpLtEaqudqsT7t/9G2GKw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=X33v0Y84I9KFSPcADczllxUu4p24D++/UKtRy3tw1X+Vx9RahyQURKnSsjiLCiBrW TlxBwFyIUslsicwyP38oyWnCkMy4f4cpV0Q6Kj69iYiSQEvdJBWhzK2Es3iy+QApnl 6LM4V+CrWt+IzxPdb42BXtrZ8JzWZ9pAYtNTHEkQlYiEOuRBUz6XFaDtkIswZnh9Pb NlImH1OLh+FRvQnVsfFuOUTtdzB8+keuaw74PspvXyi/vh8th/ai/3ft+xmTj54EiH 6fsHpzJDnZVdb46j/DsB74nK9fhyHQv6fThtZ4R+f4G+cTjqSO861exIzUvqag2gxl wGG+RwEqDzxCw== Date: Wed, 3 Dec 2025 10:02:21 -0800 From: Kees Cook To: Ard Biesheuvel Cc: linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org, Ard Biesheuvel , Will Deacon , Mark Rutland , Catalin Marinas , Mark Brown Subject: Re: [PATCH 1/2] lkdtm/bugs: Add cases for BUG and PANIC occurring in hardirq context Message-ID: <202512030959.87E62F908@keescook> References: <20251112175316.2841017-4-ardb+git@google.com> <20251112175316.2841017-5-ardb+git@google.com> Precedence: bulk X-Mailing-List: linux-efi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251112175316.2841017-5-ardb+git@google.com> On Wed, Nov 12, 2025 at 06:53:18PM +0100, Ard Biesheuvel wrote: > From: Ard Biesheuvel > > Add lkdtm cases to trigger a BUG() or panic() from hardirq context. This > is useful for testing pstore behavior being invoked from such contexts. Sorry I lost this! Thanks for the offline ping. :) > > Signed-off-by: Ard Biesheuvel > --- > drivers/misc/lkdtm/bugs.c | 53 ++++++++++++++++++++ > 1 file changed, 53 insertions(+) > > diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c > index 376047beea3d..fa05d77acb55 100644 > --- a/drivers/misc/lkdtm/bugs.c > +++ b/drivers/misc/lkdtm/bugs.c > @@ -8,6 +8,7 @@ > #include "lkdtm.h" > #include > #include > +#include > #include > #include > #include > @@ -100,11 +101,61 @@ static void lkdtm_PANIC_STOP_IRQOFF(void) > stop_machine(panic_stop_irqoff_fn, &v, cpu_online_mask); > } > > +static bool wait_for_panic; > + > +static enum hrtimer_restart panic_in_hardirq(struct hrtimer *timer) > +{ > + panic("from hard IRQ context"); > + > + wait_for_panic = false; > + return HRTIMER_NORESTART; > +} > + > +static void lkdtm_PANIC_IN_HARDIRQ(void) > +{ > + struct hrtimer timer; > + > + wait_for_panic = true; > + hrtimer_setup_on_stack(&timer, panic_in_hardirq, > + CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); > + hrtimer_start(&timer, us_to_ktime(100), HRTIMER_MODE_REL_HARD); > + > + while (wait_for_panic) > + ; > + > + hrtimer_cancel(&timer); > +} > + > static void lkdtm_BUG(void) > { > BUG(); > } > > +static bool wait_for_bug; > + > +static enum hrtimer_restart bug_in_hardirq(struct hrtimer *timer) > +{ > + BUG(); > + > + wait_for_bug = false; > + return HRTIMER_NORESTART; > +} > + > +static void lkdtm_BUG_IN_HARDIRQ(void) > +{ > + struct hrtimer timer; > + > + wait_for_bug = true; > + hrtimer_setup_on_stack(&timer, bug_in_hardirq, > + CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); > + hrtimer_start(&timer, us_to_ktime(100), HRTIMER_MODE_REL_HARD); > + > + while (wait_for_bug) > + ; > + > + hrtimer_cancel(&timer); > +} > + > static int warn_counter; > > static void lkdtm_WARNING(void) > @@ -696,7 +747,9 @@ static noinline void lkdtm_CORRUPT_PAC(void) > static struct crashtype crashtypes[] = { > CRASHTYPE(PANIC), > CRASHTYPE(PANIC_STOP_IRQOFF), > + CRASHTYPE(PANIC_IN_HARDIRQ), > CRASHTYPE(BUG), > + CRASHTYPE(BUG_IN_HARDIRQ), > CRASHTYPE(WARNING), > CRASHTYPE(WARNING_MESSAGE), > CRASHTYPE(EXCEPTION), This all looks good to me. I always ask that new tests also get added to the lkdtm selftest runner list in tools/testing/selftests/lkdtm/tests.txt IIUC, bug in hardirq will result in a panic, so both these tests will take out the entire system, so they should be skipped for the selftest. Perhaps: diff --git a/tools/testing/selftests/lkdtm/tests.txt b/tools/testing/selftests/lkdtm/tests.txt index cff124c1eddd..67cd53715d93 100644 --- a/tools/testing/selftests/lkdtm/tests.txt +++ b/tools/testing/selftests/lkdtm/tests.txt @@ -1,6 +1,8 @@ #PANIC #PANIC_STOP_IRQOFF Crashes entire system +#PANIC_IN_HARDIRQ Crashes entire system BUG kernel BUG at +#BUG_IN_HARDIRQ Crashes entire system WARNING WARNING: WARNING_MESSAGE message trigger EXCEPTION -- Kees Cook