Merge: kasan: make kasan_record_aux_stack_noalloc() the default behaviour

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/208

JIRA: https://issues.redhat.com/browse/RHEL-71050
Upstream Status: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

commit d40797d
Author: Peter Zijlstra <peterz@infradead.org>
Date:   Fri, 22 Nov 2024 16:54:51 +0100

    kasan: make kasan_record_aux_stack_noalloc() the default behaviour

    kasan_record_aux_stack_noalloc() was introduced to record a stack trace
    without allocating memory in the process.  It has been added to callers
    which were invoked while a raw_spinlock_t was held.  More and more callers
    were identified and changed over time.  Is it a good thing to have this
    while functions try their best to do a locklessly setup?  The only
    downside of having kasan_record_aux_stack() not allocate any memory is
    that we end up without a stacktrace if stackdepot runs out of memory and
    at the same stacktrace was not recorded before To quote Marco Elver from
    https://lore.kernel.org/all/CANpmjNPmQYJ7pv1N3cuU8cP18u7PP_uoZD8YxwZd4jtbof9nVQ@mail.gmail.com/

    | I'd be in favor, it simplifies things. And stack depot should be
    | able to replenish its pool sufficiently in the "non-aux" cases
    | i.e. regular allocations. Worst case we fail to record some
    | aux stacks, but I think that's only really bad if there's a bug
    | around one of these allocations. In general the probabilities
    | of this being a regression are extremely small [...]

    Make the kasan_record_aux_stack_noalloc() behaviour default as
    kasan_record_aux_stack().

    [bigeasy@linutronix.de: dressed the diff as patch]
    Link: https://lkml.kernel.org/r/20241122155451.Mb2pmeyJ@linutronix.de
    Fixes: 7cb3007 ("kasan: generic: introduce kasan_record_aux_stack_noalloc()")
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Reported-by: syzbot+39f85d612b7c20d8db48@syzkaller.appspotmail.com
    Closes: https://lore.kernel.org/all/67275485.050a0220.3c8d68.0a37.GAE@google.com
    Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
    Reviewed-by: Marco Elver <elver@google.com>
    Reviewed-by: Waiman Long <longman@redhat.com>
    Cc: Alexander Potapenko <glider@google.com>
    Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
    Cc: Ben Segall <bsegall@google.com>
    Cc: Boqun Feng <boqun.feng@gmail.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
    Cc: Dmitry Vyukov <dvyukov@google.com>
    Cc: Frederic Weisbecker <frederic@kernel.org>
    Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Jann Horn <jannh@google.com>
    Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: Josh Triplett <josh@joshtriplett.org>
    Cc: Juri Lelli <juri.lelli@redhat.com>
    Cc: <kasan-dev@googlegroups.com>
    Cc: Lai Jiangshan <jiangshanlai@gmail.com>
    Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
    Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
    Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
    Cc: Paul E. McKenney <paulmck@kernel.org>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: Roman Gushchin <roman.gushchin@linux.dev>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: syzkaller-bugs@googlegroups.com
    Cc: Tejun Heo <tj@kernel.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
    Cc: Valentin Schneider <vschneid@redhat.com>
    Cc: Vincent Guittot <vincent.guittot@linaro.org>
    Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: Zqiang <qiang.zhang1211@gmail.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Waiman Long <longman@redhat.com>

Approved-by: Phil Auld <pauld@redhat.com>
Approved-by: Wander Lairson Costa <wander@redhat.com>
Approved-by: Rafael Aquini <raquini@redhat.com>
Approved-by: Aristeu Rozanski <arozansk@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Jan Stancek <jstancek@redhat.com>

Author: jstancek

include/linux/kasan.h

@@ -488,7 +488,6 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
 void kasan_cache_shrink(struct kmem_cache *cache);
 void kasan_cache_shutdown(struct kmem_cache *cache);
 void kasan_record_aux_stack(void *ptr);
-void kasan_record_aux_stack_noalloc(void *ptr);
 
 #else /* CONFIG_KASAN_GENERIC */
 
@@ -506,7 +505,6 @@ static inline void kasan_cache_create(struct kmem_cache *cache,
 static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
 static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
 static inline void kasan_record_aux_stack(void *ptr) {}
-static inline void kasan_record_aux_stack_noalloc(void *ptr) {}
 
 #endif /* CONFIG_KASAN_GENERIC */
 

include/linux/task_work.h

@@ -19,9 +19,6 @@ enum task_work_notify_mode {
 	TWA_SIGNAL,
 	TWA_SIGNAL_NO_IPI,
 	TWA_NMI_CURRENT,
-
-	TWA_FLAGS = 0xff00,
-	TWAF_NO_ALLOC = 0x0100,
 };
 
 static inline bool task_work_pending(struct task_struct *task)

kernel/irq_work.c

@@ -147,7 +147,7 @@ bool irq_work_queue_on(struct irq_work *work, int cpu)
 	if (!irq_work_claim(work))
 		return false;
 
-	kasan_record_aux_stack_noalloc(work);
+	kasan_record_aux_stack(work);
 
 	preempt_disable();
 	if (cpu != smp_processor_id()) {

kernel/rcu/tiny.c

@@ -250,7 +250,7 @@ EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu);
 void kvfree_call_rcu(struct rcu_head *head, void *ptr)
 {
 	if (head)
-		kasan_record_aux_stack_noalloc(ptr);
+		kasan_record_aux_stack(ptr);
 
 	__kvfree_call_rcu(head, ptr);
 }

kernel/rcu/tree.c

@@ -3083,7 +3083,7 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in)
 	}
 	head->func = func;
 	head->next = NULL;
-	kasan_record_aux_stack_noalloc(head);
+	kasan_record_aux_stack(head);
 	local_irq_save(flags);
 	rdp = this_cpu_ptr(&rcu_data);
 	lazy = lazy_in && !rcu_async_should_hurry();
@@ -3817,7 +3817,7 @@ void kvfree_call_rcu(struct rcu_head *head, void *ptr)
 		return;
 	}
 
-	kasan_record_aux_stack_noalloc(ptr);
+	kasan_record_aux_stack(ptr);
 	success = add_ptr_to_bulk_krc_lock(&krcp, &flags, ptr, !head);
 	if (!success) {
 		run_page_cache_worker(krcp);

kernel/sched/core.c

@@ -10614,7 +10614,7 @@ void task_tick_mm_cid(struct rq *rq, struct task_struct *curr)
 		return;
 
 	/* No page allocation under rq lock */
-	task_work_add(curr, work, TWA_RESUME | TWAF_NO_ALLOC);
+	task_work_add(curr, work, TWA_RESUME);
 }
 
 void sched_mm_cid_exit_signals(struct task_struct *t)

kernel/task_work.c

@@ -55,26 +55,14 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
 		  enum task_work_notify_mode notify)
 {
 	struct callback_head *head;
-	int flags = notify & TWA_FLAGS;
 
-	notify &= ~TWA_FLAGS;
 	if (notify == TWA_NMI_CURRENT) {
 		if (WARN_ON_ONCE(task != current))
 			return -EINVAL;
 		if (!IS_ENABLED(CONFIG_IRQ_WORK))
 			return -EINVAL;
 	} else {
-		/*
-		 * Record the work call stack in order to print it in KASAN
-		 * reports.
-		 *
-		 * Note that stack allocation can fail if TWAF_NO_ALLOC flag
-		 * is set and new page is needed to expand the stack buffer.
-		 */
-		if (flags & TWAF_NO_ALLOC)
-			kasan_record_aux_stack_noalloc(work);
-		else
-			kasan_record_aux_stack(work);
+		kasan_record_aux_stack(work);
 	}
 
 	head = READ_ONCE(task->task_works);

kernel/workqueue.c

@@ -2180,7 +2180,7 @@ static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
 	debug_work_activate(work);
 
 	/* record the work call stack in order to print it in KASAN reports */
-	kasan_record_aux_stack_noalloc(work);
+	kasan_record_aux_stack(work);
 
 	/* we own @work, set data and link */
 	set_work_pwq(work, pwq, extra_flags);

mm/kasan/generic.c

@@ -521,7 +521,11 @@ size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object)
 			sizeof(struct kasan_free_meta) : 0);
 }
 
-static void __kasan_record_aux_stack(void *addr, depot_flags_t depot_flags)
+/*
+ * This function avoids dynamic memory allocations and thus can be called from
+ * contexts that do not allow allocating memory.
+ */
+void kasan_record_aux_stack(void *addr)
 {
 	struct slab *slab = kasan_addr_to_slab(addr);
 	struct kmem_cache *cache;
@@ -538,17 +542,7 @@ static void __kasan_record_aux_stack(void *addr, depot_flags_t depot_flags)
 		return;
 
 	alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];
-	alloc_meta->aux_stack[0] = kasan_save_stack(0, depot_flags);
-}
-
-void kasan_record_aux_stack(void *addr)
-{
-	return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_CAN_ALLOC);
-}
-
-void kasan_record_aux_stack_noalloc(void *addr)
-{
-	return __kasan_record_aux_stack(addr, 0);
+	alloc_meta->aux_stack[0] = kasan_save_stack(0, 0);
 }
 
 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)

mm/slub.c

@@ -2306,7 +2306,7 @@ bool slab_free_hook(struct kmem_cache *s, void *x, bool init,
 			 * We have to do this manually because the rcu_head is
 			 * not located inside the object.
 			 */
-			kasan_record_aux_stack_noalloc(x);
+			kasan_record_aux_stack(x);
 
 			delayed_free->object = x;
 			call_rcu(&delayed_free->head, slab_free_after_rcu_debug);