This feature will record first and last call_rcu() call stack and print two call_rcu() call stack in KASAN report.
When call_rcu() is called, we store the call_rcu() call stack into slub alloc meta-data, so that KASAN report can print rcu stack. It doesn't increase the cost of memory consumption. Because we don't enlarge struct kasan_alloc_meta size. - add two call_rcu() call stack into kasan_alloc_meta, size is 8 bytes. - remove free track from kasan_alloc_meta, size is 8 bytes. [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 Signed-off-by: Walter Wu <[email protected]> Suggested-by: Dmitry Vyukov <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Alexander Potapenko <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Josh Triplett <[email protected]> Cc: Mathieu Desnoyers <[email protected]> Cc: Lai Jiangshan <[email protected]> Cc: Joel Fernandes <[email protected]> --- include/linux/kasan.h | 2 ++ kernel/rcu/tree.c | 3 +++ lib/Kconfig.kasan | 2 ++ mm/kasan/common.c | 4 ++-- mm/kasan/generic.c | 29 +++++++++++++++++++++++++++++ mm/kasan/kasan.h | 19 +++++++++++++++++++ mm/kasan/report.c | 21 +++++++++++++++++---- 7 files changed, 74 insertions(+), 6 deletions(-) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 31314ca7c635..23b7ee00572d 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -174,11 +174,13 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; } void kasan_cache_shrink(struct kmem_cache *cache); void kasan_cache_shutdown(struct kmem_cache *cache); +void kasan_record_aux_stack(void *ptr); #else /* CONFIG_KASAN_GENERIC */ 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) {} #endif /* CONFIG_KASAN_GENERIC */ diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 06548e2ebb72..de872b6cc261 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -57,6 +57,7 @@ #include <linux/slab.h> #include <linux/sched/isolation.h> #include <linux/sched/clock.h> +#include <linux/kasan.h> #include "../time/tick-internal.h" #include "tree.h" @@ -2694,6 +2695,8 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func) trace_rcu_callback(rcu_state.name, head, rcu_segcblist_n_cbs(&rdp->cblist)); + kasan_record_aux_stack(head); + /* Go handle any RCU core processing required. */ if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) && unlikely(rcu_segcblist_is_offloaded(&rdp->cblist))) { diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index 81f5464ea9e1..56a89291f1cc 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -58,6 +58,8 @@ config KASAN_GENERIC For better error detection enable CONFIG_STACKTRACE. Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB (the resulting kernel does not boot). + Currently CONFIG_KASAN_GENERIC will print first and last call_rcu() + call stack. It doesn't increase the cost of memory consumption. config KASAN_SW_TAGS bool "Software tag-based mode" diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 2906358e42f0..8bc618289bb1 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -41,7 +41,7 @@ #include "kasan.h" #include "../slab.h" -static inline depot_stack_handle_t save_stack(gfp_t flags) +depot_stack_handle_t kasan_save_stack(gfp_t flags) { unsigned long entries[KASAN_STACK_DEPTH]; unsigned int nr_entries; @@ -54,7 +54,7 @@ static inline depot_stack_handle_t save_stack(gfp_t flags) static inline void set_track(struct kasan_track *track, gfp_t flags) { track->pid = current->pid; - track->stack = save_stack(flags); + track->stack = kasan_save_stack(flags); } void kasan_enable_current(void) diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index 56ff8885fe2e..b86880c338e2 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -325,3 +325,32 @@ DEFINE_ASAN_SET_SHADOW(f2); DEFINE_ASAN_SET_SHADOW(f3); DEFINE_ASAN_SET_SHADOW(f5); DEFINE_ASAN_SET_SHADOW(f8); + +void kasan_record_aux_stack(void *addr) +{ + struct page *page = kasan_addr_to_page(addr); + struct kmem_cache *cache; + struct kasan_alloc_meta *alloc_info; + void *object; + + if (!(page && PageSlab(page))) + return; + + cache = page->slab_cache; + object = nearest_obj(cache, page, addr); + alloc_info = get_alloc_info(cache, object); + + if (!alloc_info->rcu_stack[0]) + /* record first call_rcu() call stack */ + alloc_info->rcu_stack[0] = kasan_save_stack(GFP_NOWAIT); + else + /* record last call_rcu() call stack */ + alloc_info->rcu_stack[1] = kasan_save_stack(GFP_NOWAIT); +} + +struct kasan_track *kasan_get_aux_stack(struct kasan_alloc_meta *alloc_info, + u8 idx) +{ + return container_of(&alloc_info->rcu_stack[idx], + struct kasan_track, stack); +} diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index e8f37199d885..1cc1fb7b0de3 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -96,15 +96,28 @@ struct kasan_track { depot_stack_handle_t stack; }; +#ifdef CONFIG_KASAN_GENERIC +#define SIZEOF_PTR sizeof(void *) +#define KASAN_NR_RCU_CALL_STACKS 2 +#else /* CONFIG_KASAN_GENERIC */ #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY #define KASAN_NR_FREE_STACKS 5 #else #define KASAN_NR_FREE_STACKS 1 #endif +#endif /* CONFIG_KASAN_GENERIC */ struct kasan_alloc_meta { struct kasan_track alloc_track; +#ifdef CONFIG_KASAN_GENERIC + /* + * call_rcu() call stack is stored into struct kasan_alloc_meta. + * The free stack is stored into freed object. + */ + depot_stack_handle_t rcu_stack[KASAN_NR_RCU_CALL_STACKS]; +#else struct kasan_track free_track[KASAN_NR_FREE_STACKS]; +#endif #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY u8 free_pointer_tag[KASAN_NR_FREE_STACKS]; u8 free_track_idx; @@ -159,16 +172,22 @@ void kasan_report_invalid_free(void *object, unsigned long ip); struct page *kasan_addr_to_page(const void *addr); +depot_stack_handle_t kasan_save_stack(gfp_t flags); + #if defined(CONFIG_KASAN_GENERIC) && \ (defined(CONFIG_SLAB) || defined(CONFIG_SLUB)) void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache); void quarantine_reduce(void); void quarantine_remove_cache(struct kmem_cache *cache); +struct kasan_track *kasan_get_aux_stack(struct kasan_alloc_meta *alloc_info, + u8 idx); #else static inline void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache) { } static inline void quarantine_reduce(void) { } static inline void quarantine_remove_cache(struct kmem_cache *cache) { } +static inline struct kasan_track *kasan_get_aux_stack( + struct kasan_alloc_meta *alloc_info, u8 idx) { return NULL; } #endif #ifdef CONFIG_KASAN_SW_TAGS diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 80f23c9da6b0..f16a1a210815 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -105,9 +105,13 @@ static void end_report(unsigned long *flags) kasan_enable_current(); } -static void print_track(struct kasan_track *track, const char *prefix) +static void print_track(struct kasan_track *track, const char *prefix, + bool is_callrcu) { - pr_err("%s by task %u:\n", prefix, track->pid); + if (is_callrcu) + pr_err("%s:\n", prefix); + else + pr_err("%s by task %u:\n", prefix, track->pid); if (track->stack) { unsigned long *entries; unsigned int nr_entries; @@ -187,11 +191,20 @@ static void describe_object(struct kmem_cache *cache, void *object, if (cache->flags & SLAB_KASAN) { struct kasan_track *free_track; - print_track(&alloc_info->alloc_track, "Allocated"); + print_track(&alloc_info->alloc_track, "Allocated", false); pr_err("\n"); free_track = kasan_get_free_track(cache, object, tag); - print_track(free_track, "Freed"); + print_track(free_track, "Freed", false); pr_err("\n"); + + if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { + free_track = kasan_get_aux_stack(alloc_info, 0); + print_track(free_track, "First call_rcu() call stack", true); + pr_err("\n"); + free_track = kasan_get_aux_stack(alloc_info, 1); + print_track(free_track, "Last call_rcu() call stack", true); + pr_err("\n"); + } } describe_object_addr(cache, object, addr); -- 2.18.0
