rcu: kasan: record and print call_rcu() call stack

Patch series "kasan: memorize and print call_rcu stack", v8. This patchset improves KASAN reports by making them to have call_rcu() call stack information. It is useful for programmers to solve use-after-free or double-free memory issue. The KASAN report was as follows(cleaned up slightly): BUG: KASAN: use-after-free in kasan_rcu_reclaim+0x58/0x60 Freed by task 0: kasan_save_stack+0x24/0x50 kasan_set_track+0x24/0x38 kasan_set_free_info+0x18/0x20 __kasan_slab_free+0x10c/0x170 kasan_slab_free+0x10/0x18 kfree+0x98/0x270 kasan_rcu_reclaim+0x1c/0x60 Last call_rcu(): kasan_save_stack+0x24/0x50 kasan_record_aux_stack+0xbc/0xd0 call_rcu+0x8c/0x580 kasan_rcu_uaf+0xf4/0xf8 Generic KASAN will record the last two call_rcu() call stacks and print up to 2 call_rcu() call stacks in KASAN report. it is only suitable for generic KASAN. This feature considers the size of struct kasan_alloc_meta and kasan_free_meta, we try to optimize the structure layout and size, lets it get better memory consumption. [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437 [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ This patch (of 4): This feature will record the last two call_rcu() call stacks and prints up to 2 call_rcu() call stacks in KASAN report. When call_rcu() is called, we store the call_rcu() call stack into slub alloc meta-data, so that the KASAN report can print rcu stack. [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437 [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ [walter-zh.wu@mediatek.com: build fix] Link: http://lkml.kernel.org/r/20200710162401.23816-1-walter-zh.wu@mediatek.com

Walter Wu committed 6 years ago

Commit 26e760c1 parent ac4766b6 files · +59 −7Browse files

Unified · Split

6 files

include/linux/kasan.h +2 −0
kernel/rcu/tree.c +2 −0
mm/kasan/common.c +2 −2
mm/kasan/generic.c +21 −0
mm/kasan/kasan.h +9 −0
mm/kasan/report.c +23 −5

include/linux/kasan.h+2−0

@@ -174,11 +174,13 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; } · 173 unmodified lines
174	174
175	175	void kasan_cache_shrink(struct kmem_cache *cache);
176	176	void kasan_cache_shutdown(struct kmem_cache *cache);
	177	+void kasan_record_aux_stack(void *ptr);
177	178
178	179	#else /* CONFIG_KASAN_GENERIC */
179	180
180	181	static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
181	182	static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
	183	+static inline void kasan_record_aux_stack(void *ptr) {}
182	184
183	185	#endif /* CONFIG_KASAN_GENERIC */
184	186

kernel/rcu/tree.c+2−0

@@ -59,6 +59,7 @@ · 58 unmodified lines
59	59	#include <linux/sched/clock.h>
60	60	#include <linux/vmalloc.h>
61	61	#include <linux/mm.h>
	62	+#include <linux/kasan.h>
62	63	#include "../time/tick-internal.h"
63	64
64	65	#include "tree.h"
@@ -2890,6 +2891,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func) · 2825 unmodified lines
2890	2891	head->func = func;
2891	2892	head->next = NULL;
2892	2893	local_irq_save(flags);
	2894	+ kasan_record_aux_stack(head);
2893	2895	rdp = this_cpu_ptr(&rcu_data);
2894	2896
2895	2897	/* Add the callback to our list. */

mm/kasan/common.c+2−2

@@ -40,7 +40,7 @@ · 39 unmodified lines
40	40	#include "kasan.h"
41	41	#include "../slab.h"
42	42
43		−static inline depot_stack_handle_t save_stack(gfp_t flags)
	43	+depot_stack_handle_t kasan_save_stack(gfp_t flags)
44	44	{
45	45	unsigned long entries[KASAN_STACK_DEPTH];
46	46	unsigned int nr_entries;
@@ -53,7 +53,7 @@ static inline depot_stack_handle_t save_stack(gfp_t flags) · 6 unmodified lines
53	53	static inline void set_track(struct kasan_track *track, gfp_t flags)
54	54	{
55	55	track->pid = current->pid;
56		− track->stack = save_stack(flags);
	56	+ track->stack = kasan_save_stack(flags);
57	57	}
58	58
59	59	void kasan_enable_current(void)

mm/kasan/generic.c+21−0

@@ -324,3 +324,24 @@ DEFINE_ASAN_SET_SHADOW(f2); · 323 unmodified lines
324	324	DEFINE_ASAN_SET_SHADOW(f3);
325	325	DEFINE_ASAN_SET_SHADOW(f5);
326	326	DEFINE_ASAN_SET_SHADOW(f8);
	327	+
	328	+void kasan_record_aux_stack(void *addr)
	329	+{
	330	+ struct page *page = kasan_addr_to_page(addr);
	331	+ struct kmem_cache *cache;
	332	+ struct kasan_alloc_meta *alloc_info;
	333	+ void *object;
	334	+
	335	+ if (!(page && PageSlab(page)))
	336	+ return;
	337	+
	338	+ cache = page->slab_cache;
	339	+ object = nearest_obj(cache, page, addr);
	340	+ alloc_info = get_alloc_info(cache, object);
	341	+
	342	+ /*
	343	+ * record the last two call_rcu() call stacks.
	344	+ */
	345	+ alloc_info->aux_stack[1] = alloc_info->aux_stack[0];
	346	+ alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
	347	+}

mm/kasan/kasan.h+9−0

@@ -104,6 +104,13 @@ struct kasan_track { · 103 unmodified lines
104	104
105	105	struct kasan_alloc_meta {
106	106	struct kasan_track alloc_track;
	107	+#ifdef CONFIG_KASAN_GENERIC
	108	+ /*
	109	+ * call_rcu() call stack is stored into struct kasan_alloc_meta.
	110	+ * The free stack is stored into struct kasan_free_meta.
	111	+ */
	112	+ depot_stack_handle_t aux_stack[2];
	113	+#endif
107	114	struct kasan_track free_track[KASAN_NR_FREE_STACKS];
108	115	#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
109	116	u8 free_pointer_tag[KASAN_NR_FREE_STACKS];
@@ -159,6 +166,8 @@ void kasan_report_invalid_free(void *object, unsigned long ip); · 49 unmodified lines
159	166
160	167	struct page kasan_addr_to_page(const void addr);
161	168
	169	+depot_stack_handle_t kasan_save_stack(gfp_t flags);
	170	+
162	171	#if defined(CONFIG_KASAN_GENERIC) && \
163	172	(defined(CONFIG_SLAB) \|\| defined(CONFIG_SLUB))
164	173	void quarantine_put(struct kasan_free_meta info, struct kmem_cache cache);

mm/kasan/report.c+23−5

@@ -106,15 +106,20 @@ static void end_report(unsigned long *flags) · 105 unmodified lines
106	106	kasan_enable_current();
107	107	}
108	108
	109	+static void print_stack(depot_stack_handle_t stack)
	110	+{
	111	+ unsigned long *entries;
	112	+ unsigned int nr_entries;
	113	+
	114	+ nr_entries = stack_depot_fetch(stack, &entries);
	115	+ stack_trace_print(entries, nr_entries, 0);
	116	+}
	117	+
109	118	static void print_track(struct kasan_track track, const char prefix)
110	119	{
111	120	pr_err("%s by task %u:\n", prefix, track->pid);
112	121	if (track->stack) {
113		− unsigned long *entries;
114		− unsigned int nr_entries;
115		−
116		− nr_entries = stack_depot_fetch(track->stack, &entries);
117		− stack_trace_print(entries, nr_entries, 0);
	122	+ print_stack(track->stack);
118	123	} else {
119	124	pr_err("(stack is not available)\n");
120	125	}
@@ -193,6 +198,19 @@ static void describe_object(struct kmem_cache cache, void object, · 72 unmodified lines
193	198	free_track = kasan_get_free_track(cache, object, tag);
194	199	print_track(free_track, "Freed");
195	200	pr_err("\n");
	201	+
	202	+#ifdef CONFIG_KASAN_GENERIC
	203	+ if (alloc_info->aux_stack[0]) {
	204	+ pr_err("Last call_rcu():\n");
	205	+ print_stack(alloc_info->aux_stack[0]);
	206	+ pr_err("\n");
	207	+ }
	208	+ if (alloc_info->aux_stack[1]) {
	209	+ pr_err("Second to last call_rcu():\n");
	210	+ print_stack(alloc_info->aux_stack[1]);
	211	+ pr_err("\n");
	212	+ }
	213	+#endif
196	214	}
197	215
198	216	describe_object_addr(cache, object, addr);

rcu: kasan: record and print call_rcu() call stack

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