This feature will record the last two call_rcu() call stack 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 Signed-off-by: Walter Wu <walter-zh.wu@xxxxxxxxxxxx> Suggested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx> Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx> Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> --- include/linux/kasan.h | 2 ++ kernel/rcu/tree.c | 2 ++ lib/Kconfig.kasan | 2 ++ mm/kasan/common.c | 4 ++-- mm/kasan/generic.c | 20 ++++++++++++++++++++ mm/kasan/kasan.h | 10 ++++++++++ mm/kasan/report.c | 24 ++++++++++++++++++++++++ 7 files changed, 62 insertions(+), 2 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..36a4ff7f320b 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" @@ -2668,6 +2669,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func) head->func = func; head->next = NULL; local_irq_save(flags); + kasan_record_aux_stack(head); rdp = this_cpu_ptr(&rcu_data); /* Add the callback to our list. */ diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index 81f5464ea9e1..4e83cf6e3caa 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). + In generic mode KASAN prints the last two call_rcu() call stacks in + reports. 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..78d8e0a75a8a 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -325,3 +325,23 @@ 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); + + /* record last two call_rcu() call stacks */ + if (alloc_info->rcu_stack[0]) + alloc_info->rcu_stack[1] = alloc_info->rcu_stack[0]; + alloc_info->rcu_stack[0] = kasan_save_stack(GFP_NOWAIT); +} diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index e8f37199d885..870c5dd07756 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -104,7 +104,15 @@ struct kasan_track { 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 struct kasan_free_meta. + */ + depot_stack_handle_t rcu_stack[2]; +#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; @@ -159,6 +167,8 @@ 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); diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 80f23c9da6b0..5ee66cf7e27c 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -179,6 +179,17 @@ static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, return &alloc_meta->free_track[i]; } +#ifdef CONFIG_KASAN_GENERIC +static void print_stack(depot_stack_handle_t stack) +{ + unsigned long *entries; + unsigned int nr_entries; + + nr_entries = stack_depot_fetch(stack, &entries); + stack_trace_print(entries, nr_entries, 0); +} +#endif + static void describe_object(struct kmem_cache *cache, void *object, const void *addr, u8 tag) { @@ -192,6 +203,19 @@ static void describe_object(struct kmem_cache *cache, void *object, free_track = kasan_get_free_track(cache, object, tag); print_track(free_track, "Freed"); pr_err("\n"); + +#ifdef CONFIG_KASAN_GENERIC + if (alloc_info->rcu_stack[0]) { + pr_err("Last one call_rcu() call stack:\n"); + print_stack(alloc_info->rcu_stack[0]); + pr_err("\n"); + } + if (alloc_info->rcu_stack[1]) { + pr_err("Second to last call_rcu() call stack:\n"); + print_stack(alloc_info->rcu_stack[1]); + pr_err("\n"); + } +#endif } describe_object_addr(cache, object, addr); -- 2.18.0
