History

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
  1. include/linux/kasan.h +2 −0
  2. kernel/rcu/tree.c +2 −0
  3. mm/kasan/common.c +2 −2
  4. mm/kasan/generic.c +21 −0
  5. mm/kasan/kasan.h +9 −0
  6. 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
175void kasan_cache_shrink(struct kmem_cache *cache);175void kasan_cache_shrink(struct kmem_cache *cache);
176void kasan_cache_shutdown(struct kmem_cache *cache);176void kasan_cache_shutdown(struct kmem_cache *cache);
177void kasan_record_aux_stack(void *ptr);
177 178
178#else /* CONFIG_KASAN_GENERIC */179#else /* CONFIG_KASAN_GENERIC */
179 180
180static inline void kasan_cache_shrink(struct kmem_cache *cache) {}181static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
181static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}182static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
183static inline void kasan_record_aux_stack(void *ptr) {}
182 184
183#endif /* CONFIG_KASAN_GENERIC */185#endif /* CONFIG_KASAN_GENERIC */
184 186
kernel/rcu/tree.c+2−0
@@ -59,6 +59,7 @@ · 58 unmodified lines
59#include <linux/sched/clock.h>59#include <linux/sched/clock.h>
60#include <linux/vmalloc.h>60#include <linux/vmalloc.h>
61#include <linux/mm.h>61#include <linux/mm.h>
62#include <linux/kasan.h>
62#include "../time/tick-internal.h"63#include "../time/tick-internal.h"
63 64
64#include "tree.h"65#include "tree.h"
@@ -2890,6 +2891,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func) · 2825 unmodified lines
2890 head->func = func;2891 head->func = func;
2891 head->next = NULL;2892 head->next = NULL;
2892 local_irq_save(flags);2893 local_irq_save(flags);
2894 kasan_record_aux_stack(head);
2893 rdp = this_cpu_ptr(&rcu_data);2895 rdp = this_cpu_ptr(&rcu_data);
2894 2896
2895 /* Add the callback to our list. */2897 /* Add the callback to our list. */
mm/kasan/common.c+2−2
@@ -40,7 +40,7 @@ · 39 unmodified lines
40#include "kasan.h"40#include "kasan.h"
41#include "../slab.h"41#include "../slab.h"
42 42
43static inline depot_stack_handle_t save_stack(gfp_t flags)43depot_stack_handle_t kasan_save_stack(gfp_t flags)
44{44{
45 unsigned long entries[KASAN_STACK_DEPTH];45 unsigned long entries[KASAN_STACK_DEPTH];
46 unsigned int nr_entries;46 unsigned int nr_entries;
@@ -53,7 +53,7 @@ static inline depot_stack_handle_t save_stack(gfp_t flags) · 6 unmodified lines
53static inline void set_track(struct kasan_track *track, gfp_t flags)53static inline void set_track(struct kasan_track *track, gfp_t flags)
54{54{
55 track->pid = current->pid;55 track->pid = current->pid;
56 track->stack = save_stack(flags);56 track->stack = kasan_save_stack(flags);
57}57}
58 58
59void kasan_enable_current(void)59void kasan_enable_current(void)
mm/kasan/generic.c+21−0
@@ -324,3 +324,24 @@ DEFINE_ASAN_SET_SHADOW(f2); · 323 unmodified lines
324DEFINE_ASAN_SET_SHADOW(f3);324DEFINE_ASAN_SET_SHADOW(f3);
325DEFINE_ASAN_SET_SHADOW(f5);325DEFINE_ASAN_SET_SHADOW(f5);
326DEFINE_ASAN_SET_SHADOW(f8);326DEFINE_ASAN_SET_SHADOW(f8);
327
328void 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
105struct kasan_alloc_meta {105struct kasan_alloc_meta {
106 struct kasan_track alloc_track;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 struct kasan_track free_track[KASAN_NR_FREE_STACKS];114 struct kasan_track free_track[KASAN_NR_FREE_STACKS];
108#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY115#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
109 u8 free_pointer_tag[KASAN_NR_FREE_STACKS];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
160struct page *kasan_addr_to_page(const void *addr);167struct page *kasan_addr_to_page(const void *addr);
161 168
169depot_stack_handle_t kasan_save_stack(gfp_t flags);
170
162#if defined(CONFIG_KASAN_GENERIC) && \171#if defined(CONFIG_KASAN_GENERIC) && \
163 (defined(CONFIG_SLAB) || defined(CONFIG_SLUB))172 (defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
164void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache);173void 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 kasan_enable_current();106 kasan_enable_current();
107}107}
108 108
109static 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
109static void print_track(struct kasan_track *track, const char *prefix)118static void print_track(struct kasan_track *track, const char *prefix)
110{119{
111 pr_err("%s by task %u:\n", prefix, track->pid);120 pr_err("%s by task %u:\n", prefix, track->pid);
112 if (track->stack) {121 if (track->stack) {
113 unsigned long *entries;122 print_stack(track->stack);
114 unsigned int nr_entries;
115
116 nr_entries = stack_depot_fetch(track->stack, &entries);
117 stack_trace_print(entries, nr_entries, 0);
118 } else {123 } else {
119 pr_err("(stack is not available)\n");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 free_track = kasan_get_free_track(cache, object, tag);198 free_track = kasan_get_free_track(cache, object, tag);
194 print_track(free_track, "Freed");199 print_track(free_track, "Freed");
195 pr_err("\n");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 describe_object_addr(cache, object, addr);216 describe_object_addr(cache, object, addr);

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