Introduce various lockdep related crash tests.

Signed-off-by: Tzung-Bi Shih tzungbi@kernel.org --- v3: - Add some entries in tools/testing/selftests/lkdtm/tests.txt.

v2: https://lore.kernel.org/all/20251117033337.3730681-1-tzungbi@kernel.org/ - Fix "warning: suggest braces around empty body in an 'else' statement [-Wempty-body]" reported by 0day test robot.

v1: https://lore.kernel.org/lkml/20251114062535.1827309-1-tzungbi@kernel.org/T/#...

drivers/misc/lkdtm/Makefile | 1 + drivers/misc/lkdtm/core.c | 1 + drivers/misc/lkdtm/lkdtm.h | 1 + drivers/misc/lkdtm/lockdep.c | 98 +++++++++++++++++++++++++ tools/testing/selftests/lkdtm/tests.txt | 8 ++ 5 files changed, 109 insertions(+) create mode 100644 drivers/misc/lkdtm/lockdep.c

diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile index 03ebe33185f9..830b71c8e6a0 100644 --- a/drivers/misc/lkdtm/Makefile +++ b/drivers/misc/lkdtm/Makefile @@ -11,6 +11,7 @@ lkdtm-$(CONFIG_LKDTM) += usercopy.o lkdtm-$(CONFIG_LKDTM) += kstack_erase.o lkdtm-$(CONFIG_LKDTM) += cfi.o lkdtm-$(CONFIG_LKDTM) += fortify.o +lkdtm-$(CONFIG_LKDTM) += lockdep.o lkdtm-$(CONFIG_PPC_64S_HASH_MMU) += powerpc.o

KASAN_SANITIZE_stackleak.o := n diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c index 5732fd59a227..43e91388940f 100644 --- a/drivers/misc/lkdtm/core.c +++ b/drivers/misc/lkdtm/core.c @@ -96,6 +96,7 @@ static const struct crashtype_category *crashtype_categories[] = { &stackleak_crashtypes, &cfi_crashtypes, &fortify_crashtypes, + &lockdep_crashtypes, #ifdef CONFIG_PPC_64S_HASH_MMU &powerpc_crashtypes, #endif diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h index 015e0484026b..d2d97e6f323e 100644 --- a/drivers/misc/lkdtm/lkdtm.h +++ b/drivers/misc/lkdtm/lkdtm.h @@ -84,6 +84,7 @@ extern struct crashtype_category usercopy_crashtypes; extern struct crashtype_category stackleak_crashtypes; extern struct crashtype_category cfi_crashtypes; extern struct crashtype_category fortify_crashtypes; +extern struct crashtype_category lockdep_crashtypes; extern struct crashtype_category powerpc_crashtypes;

/* Each category's init/exit routines. */ diff --git a/drivers/misc/lkdtm/lockdep.c b/drivers/misc/lkdtm/lockdep.c new file mode 100644 index 000000000000..e029e9e60ce6 --- /dev/null +++ b/drivers/misc/lkdtm/lockdep.c @@ -0,0 +1,98 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2025 Google LLC + * + * Tests related to lockdep warnings. + */ +#include "lkdtm.h" +#include <linux/cleanup.h> +#include <linux/irqflags.h> +#include <linux/mutex.h> +#include <linux/spinlock.h> +#include <linux/srcu.h> + +static DEFINE_SPINLOCK(lock_A); +static DEFINE_SPINLOCK(lock_B); + +/* For "WARNING: possible circular locking dependency detected". */ +static void lkdtm_LOCKDEP_CIRCULAR_LOCK(void) +{ + scoped_guard(spinlock, &lock_A) + scoped_guard(spinlock, &lock_B) {} + scoped_guard(spinlock, &lock_B) + scoped_guard(spinlock, &lock_A) {} +} + +/* For "WARNING: possible recursive locking detected". */ +static void lkdtm_LOCKDEP_RECURSIVE_LOCK(void) +{ + guard(spinlock)(&lock_A); + guard(spinlock)(&lock_A); +} + +/* For "WARNING: inconsistent lock state". */ +static void lkdtm_LOCKDEP_INCONSISTENT_LOCK(void) +{ + lockdep_softirq_enter(); + scoped_guard(spinlock, &lock_A) {} + lockdep_softirq_exit(); + + scoped_guard(spinlock, &lock_A) {} +} + +/* For "WARNING: Nested lock was not taken". */ +static void lkdtm_LOCKDEP_NESTED_LOCK_NOT_HELD(void) +{ + spin_lock_nest_lock(&lock_B, &lock_A); +} + +/* For "WARNING: bad unlock balance detected!". */ +static void lkdtm_LOCKDEP_BAD_UNLOCK_BALANCE(void) +{ + spin_unlock(&lock_A); +} + +/* For "WARNING: held lock freed!". */ +static void lkdtm_LOCKDEP_HELD_LOCK_FREED(void) +{ + spin_lock(&lock_A); + spin_lock_init(&lock_A); +} + +/* For "WARNING: lock held when returning to user space!". */ +static void lkdtm_LOCKDEP_HELD_LOCK(void) +{ + spin_lock(&lock_A); +} + +/* For "WARNING: suspicious RCU usage". */ +static void lkdtm_LOCKDEP_SUSPICIOUS_RCU(void) +{ + struct srcu_struct srcu; + void __rcu *res = NULL; + int idx; + + init_srcu_struct(&srcu); + + idx = srcu_read_lock(&srcu); + rcu_dereference(res); + srcu_read_unlock(&srcu, idx); + + cleanup_srcu_struct(&srcu); +} + +static struct crashtype crashtypes[] = { + CRASHTYPE(LOCKDEP_CIRCULAR_LOCK), + CRASHTYPE(LOCKDEP_RECURSIVE_LOCK), + CRASHTYPE(LOCKDEP_INCONSISTENT_LOCK), + CRASHTYPE(LOCKDEP_NESTED_LOCK_NOT_HELD), + CRASHTYPE(LOCKDEP_BAD_UNLOCK_BALANCE), + CRASHTYPE(LOCKDEP_HELD_LOCK_FREED), + CRASHTYPE(LOCKDEP_HELD_LOCK), + CRASHTYPE(LOCKDEP_SUSPICIOUS_RCU), +}; + +struct crashtype_category lockdep_crashtypes = { + .crashtypes = crashtypes, + .len = ARRAY_SIZE(crashtypes), +}; diff --git a/tools/testing/selftests/lkdtm/tests.txt b/tools/testing/selftests/lkdtm/tests.txt index cff124c1eddd..7b32dece3d3a 100644 --- a/tools/testing/selftests/lkdtm/tests.txt +++ b/tools/testing/selftests/lkdtm/tests.txt @@ -83,3 +83,11 @@ FORTIFY_STR_MEMBER detected buffer overflow FORTIFY_MEM_OBJECT detected buffer overflow FORTIFY_MEM_MEMBER detected field-spanning write PPC_SLB_MULTIHIT Recovered +#LOCKDEP_CIRCULAR_LOCK Lockdep can only trigger once +#LOCKDEP_RECURSIVE_LOCK Hangs the system +#LOCKDEP_INCONSISTENT_LOCK Lockdep can only trigger once +#LOCKDEP_NESTED_LOCK_NOT_HELD Cause a deadlock in subsequent lockdep tests +#LOCKDEP_BAD_UNLOCK_BALANCE Lockdep can only trigger once +#LOCKDEP_HELD_LOCK_FREED Lockdep can only trigger once +#LOCKDEP_HELD_LOCK Cause a deadlock in subsequent lockdep tests +#LOCKDEP_SUSPICIOUS_RCU Lockdep can only trigger once