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McKenney" , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , Andrew Morton CC: , , , , wsd_upstream , , Walter Wu Subject: [PATCH v2 1/3] rcu/kasan: record and print call_rcu() call stack Date: Mon, 11 May 2020 10:31:11 +0800 Message-ID: <20200511023111.15310-1-walter-zh.wu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 Suggested-by: Dmitry Vyukov Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Andrew Morton Cc: Paul E. McKenney Cc: Josh Triplett Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes --- 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 #include #include +#include #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); From patchwork Mon May 11 02:31:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Walter Wu X-Patchwork-Id: 11539623 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3CE14913 for ; 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Mon, 11 May 2020 10:31:55 +0800 From: Walter Wu To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Matthias Brugger CC: , , , , wsd_upstream , , Walter Wu Subject: [PATCH v2 2/3] kasan: record and print the free track Date: Mon, 11 May 2020 10:31:53 +0800 Message-ID: <20200511023153.15376-1-walter-zh.wu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In order not to enlarge slub meta-data size, so we move free track from slub meta-data (struct kasan_alloc_meta) into freed object. Modification of struct kasan_alloc_meta: - add two call_rcu() stack into kasan_alloc_meta, size is 8 bytes. - remove free track from kasan_alloc_meta, size is 8 bytes. Because free track is stored in freed object, so that if it is an allocation objects, then it will not have free track information in KASAN report. This feature is only suitable for generic KASAN, because we need to know whether objects are allocation or free. - if slub object is allocation state, it will not print free stack. - if slub oeject is free state, it will print free stack. [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437 Signed-off-by: Walter Wu Suggested-by: Dmitry Vyukov Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Alexander Potapenko --- mm/kasan/common.c | 22 ++-------------------- mm/kasan/generic.c | 22 ++++++++++++++++++++++ mm/kasan/kasan.h | 4 ++++ mm/kasan/report.c | 28 +++++----------------------- mm/kasan/tags.c | 37 +++++++++++++++++++++++++++++++++++++ 5 files changed, 70 insertions(+), 43 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 8bc618289bb1..47b53912f322 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -51,7 +51,7 @@ depot_stack_handle_t kasan_save_stack(gfp_t flags) return stack_depot_save(entries, nr_entries, flags); } -static inline void set_track(struct kasan_track *track, gfp_t flags) +void kasan_set_track(struct kasan_track *track, gfp_t flags) { track->pid = current->pid; track->stack = kasan_save_stack(flags); @@ -299,24 +299,6 @@ struct kasan_free_meta *get_free_info(struct kmem_cache *cache, return (void *)object + cache->kasan_info.free_meta_offset; } - -static void kasan_set_free_info(struct kmem_cache *cache, - void *object, u8 tag) -{ - struct kasan_alloc_meta *alloc_meta; - u8 idx = 0; - - alloc_meta = get_alloc_info(cache, object); - -#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY - idx = alloc_meta->free_track_idx; - alloc_meta->free_pointer_tag[idx] = tag; - alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS; -#endif - - set_track(&alloc_meta->free_track[idx], GFP_NOWAIT); -} - void kasan_poison_slab(struct page *page) { unsigned long i; @@ -492,7 +474,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object, KASAN_KMALLOC_REDZONE); if (cache->flags & SLAB_KASAN) - set_track(&get_alloc_info(cache, object)->alloc_track, flags); + kasan_set_track(&get_alloc_info(cache, object)->alloc_track, flags); return set_tag(object, tag); } diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index b86880c338e2..dacff05a8107 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -354,3 +354,25 @@ struct kasan_track *kasan_get_aux_stack(struct kasan_alloc_meta *alloc_info, return container_of(&alloc_info->rcu_stack[idx], struct kasan_track, stack); } + +void kasan_set_free_info(struct kmem_cache *cache, + void *object, u8 tag) +{ + /* store free track into freed object */ + kasan_set_track((struct kasan_track *)(object + SIZEOF_PTR), GFP_NOWAIT); +} + +struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, + void *object, u8 tag, const void *addr) +{ + u8 *shadow_addr = (u8 *)kasan_mem_to_shadow(addr); + + /* + * Only the freed object can get free track, + * because free track information is stored to freed object. + */ + if (*shadow_addr == KASAN_KMALLOC_FREE) + return (struct kasan_track *)(object + SIZEOF_PTR); + else + return NULL; +} diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 1cc1fb7b0de3..f88d13f86ed3 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -173,6 +173,10 @@ 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); +void kasan_set_track(struct kasan_track *track, gfp_t flags); +void kasan_set_free_info(struct kmem_cache *cache, void *object, u8 tag); +struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, + void *object, u8 tag, const void *addr); #if defined(CONFIG_KASAN_GENERIC) && \ (defined(CONFIG_SLAB) || defined(CONFIG_SLUB)) diff --git a/mm/kasan/report.c b/mm/kasan/report.c index f16a1a210815..51813f02992c 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -163,26 +163,6 @@ static void describe_object_addr(struct kmem_cache *cache, void *object, (void *)(object_addr + cache->object_size)); } -static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, - void *object, u8 tag) -{ - struct kasan_alloc_meta *alloc_meta; - int i = 0; - - alloc_meta = get_alloc_info(cache, object); - -#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY - for (i = 0; i < KASAN_NR_FREE_STACKS; i++) { - if (alloc_meta->free_pointer_tag[i] == tag) - break; - } - if (i == KASAN_NR_FREE_STACKS) - i = alloc_meta->free_track_idx; -#endif - - return &alloc_meta->free_track[i]; -} - static void describe_object(struct kmem_cache *cache, void *object, const void *addr, u8 tag) { @@ -193,9 +173,11 @@ static void describe_object(struct kmem_cache *cache, void *object, 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", false); - pr_err("\n"); + free_track = kasan_get_free_track(cache, object, tag, addr); + if (free_track) { + print_track(free_track, "Freed", false); + pr_err("\n"); + } if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { free_track = kasan_get_aux_stack(alloc_info, 0); diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c index 25b7734e7013..30a27f8c1e6e 100644 --- a/mm/kasan/tags.c +++ b/mm/kasan/tags.c @@ -162,3 +162,40 @@ void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size) kasan_poison_shadow((void *)addr, size, tag); } EXPORT_SYMBOL(__hwasan_tag_memory); + +void kasan_set_free_info(struct kmem_cache *cache, + void *object, u8 tag) +{ + struct kasan_alloc_meta *alloc_meta; + u8 idx = 0; + + alloc_meta = get_alloc_info(cache, object); + +#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY + idx = alloc_meta->free_track_idx; + alloc_meta->free_pointer_tag[idx] = tag; + alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS; +#endif + + kasan_set_track(&alloc_meta->free_track[idx], GFP_NOWAIT); +} + +struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, + void *object, u8 tag, const void *addr) +{ + struct kasan_alloc_meta *alloc_meta; + int i = 0; + + alloc_meta = get_alloc_info(cache, object); + +#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY + for (i = 0; i < KASAN_NR_FREE_STACKS; i++) { + if (alloc_meta->free_pointer_tag[i] == tag) + break; + } + if (i == KASAN_NR_FREE_STACKS) + i = alloc_meta->free_track_idx; +#endif + + return &alloc_meta->free_track[i]; +} From patchwork Mon May 11 02:32:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Walter Wu X-Patchwork-Id: 11539635 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 744D3913 for ; 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Mon, 11 May 2020 10:32:31 +0800 From: Walter Wu To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Jonathan Corbet CC: , , , , wsd_upstream , , Walter Wu Subject: [PATCH v2 3/3] kasan: update documentation for generic kasan Date: Mon, 11 May 2020 10:32:31 +0800 Message-ID: <20200511023231.15437-1-walter-zh.wu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-Bogosity: Ham, tests=bogofilter, spamicity=0.081756, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Generic KASAN will support to record first and last call_rcu() call stack and print them in KASAN report. so we update documentation. Signed-off-by: Walter Wu Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Jonathan Corbet --- Documentation/dev-tools/kasan.rst | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst index c652d740735d..d4efcfde9fff 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -193,6 +193,12 @@ function calls GCC directly inserts the code to check the shadow memory. This option significantly enlarges kernel but it gives x1.1-x2 performance boost over outline instrumented kernel. +Currently generic KASAN can print call_rcu() call stack in KASAN report, it +can't increase the cost of memory consumption, but it has one limitations. +It can't get both call_rcu() call stack and free stack, so that it can't +print free stack for allocation objects in KASAN report. This feature is +only suitable for generic KASAN. + Software tag-based KASAN ~~~~~~~~~~~~~~~~~~~~~~~~