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McKenney" , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , Andrew Morton CC: , , , , wsd_upstream , , Walter Wu Subject: [PATCH 1/3] rcu/kasan: record and print call_rcu() call stack Date: Wed, 6 May 2020 13:20:46 +0800 Message-ID: <20200506052046.14451-1-walter-zh.wu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-TM-SNTS-SMTP: 207E808D1826991DB0A16DB3C4D0C374BC1D58B8654CEFD3C6BB5AFBE7FBB2F42000:8 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: When call_rcu() is called, we store the call_rcu() call stack into slub alloc meta-data, so that KASAN report prints call_rcu() information. We add new KASAN_RCU_STACK_RECORD configuration option. It will record first and last call_rcu() call stack and KASAN report will print two call_rcu() call stack. This option 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 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 | 7 +++++++ kernel/rcu/tree.c | 4 ++++ lib/Kconfig.kasan | 11 +++++++++++ mm/kasan/common.c | 23 +++++++++++++++++++++++ mm/kasan/kasan.h | 12 ++++++++++++ mm/kasan/report.c | 33 +++++++++++++++++++++++++++------ 6 files changed, 84 insertions(+), 6 deletions(-) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 31314ca7c635..5eeece6893cd 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -96,6 +96,12 @@ size_t kasan_metadata_size(struct kmem_cache *cache); bool kasan_save_enable_multi_shot(void); void kasan_restore_multi_shot(bool enabled); +#ifdef CONFIG_KASAN_RCU_STACK_RECORD +void kasan_record_callrcu(void *ptr); +#else +static inline void kasan_record_callrcu(void *ptr) {} +#endif + #else /* CONFIG_KASAN */ static inline void kasan_unpoison_shadow(const void *address, size_t size) {} @@ -165,6 +171,7 @@ static inline void kasan_remove_zero_shadow(void *start, static inline void kasan_unpoison_slab(const void *ptr) { } static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; } +static inline void kasan_record_callrcu(void *ptr) {} #endif /* CONFIG_KASAN */ diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 06548e2ebb72..145c79becf7b 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 +2695,9 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func) trace_rcu_callback(rcu_state.name, head, rcu_segcblist_n_cbs(&rdp->cblist)); + if (IS_ENABLED(CONFIG_KASAN_RCU_STACK_RECORD)) + kasan_record_callrcu(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..022934049cc2 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -158,6 +158,17 @@ config KASAN_VMALLOC for KASAN to detect more sorts of errors (and to support vmapped stacks), but at the cost of higher memory usage. +config KASAN_RCU_STACK_RECORD + bool "Record and print call_rcu() call stack" + depends on KASAN_GENERIC + help + By default, the KASAN report doesn't print call_rcu() call stack. + It is very difficult to analyze memory issues(e.g., use-after-free). + + Enabling this option will print first and last call_rcu() call stack. + It doesn't enlarge slub alloc meta-data size, so it doesn't increase + the cost of memory consumption. + config TEST_KASAN tristate "Module for testing KASAN for bug detection" depends on m && KASAN diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 2906358e42f0..32d422bdf127 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -299,6 +299,29 @@ struct kasan_free_meta *get_free_info(struct kmem_cache *cache, return (void *)object + cache->kasan_info.free_meta_offset; } +#ifdef CONFIG_KASAN_RCU_STACK_RECORD +void kasan_record_callrcu(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_free_stack[0]) + /* record first call_rcu() call stack */ + alloc_info->rcu_free_stack[0] = save_stack(GFP_NOWAIT); + else + /* record last call_rcu() call stack */ + alloc_info->rcu_free_stack[1] = save_stack(GFP_NOWAIT); +} +#endif static void kasan_set_free_info(struct kmem_cache *cache, void *object, u8 tag) diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index e8f37199d885..adc105b9cd07 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -96,15 +96,27 @@ struct kasan_track { depot_stack_handle_t stack; }; +#ifdef CONFIG_KASAN_RCU_STACK_RECORD +#define BYTES_PER_WORD 4 +#define KASAN_NR_RCU_FREE_STACKS 2 +#else /* CONFIG_KASAN_RCU_STACK_RECORD */ #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY #define KASAN_NR_FREE_STACKS 5 #else #define KASAN_NR_FREE_STACKS 1 #endif +#endif /* CONFIG_KASAN_RCU_STACK_RECORD */ struct kasan_alloc_meta { struct kasan_track alloc_track; +#ifdef CONFIG_KASAN_RCU_STACK_RECORD + /* call_rcu() call stack is stored into kasan_alloc_meta. + * free stack is stored into freed object. + */ + depot_stack_handle_t rcu_free_stack[KASAN_NR_RCU_FREE_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; diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 80f23c9da6b0..7aaccc70b65b 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; @@ -159,8 +163,22 @@ static void describe_object_addr(struct kmem_cache *cache, void *object, (void *)(object_addr + cache->object_size)); } +#ifdef CONFIG_KASAN_RCU_STACK_RECORD +static void kasan_print_rcu_free_stack(struct kasan_alloc_meta *alloc_info) +{ + struct kasan_track free_track; + + free_track.stack = alloc_info->rcu_free_stack[0]; + print_track(&free_track, "First call_rcu() call stack", true); + pr_err("\n"); + free_track.stack = alloc_info->rcu_free_stack[1]; + print_track(&free_track, "Last call_rcu() call stack", true); + pr_err("\n"); +} +#endif + static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, - void *object, u8 tag) + void *object, u8 tag, const void *addr) { struct kasan_alloc_meta *alloc_meta; int i = 0; @@ -187,11 +205,14 @@ 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"); + free_track = kasan_get_free_track(cache, object, tag, addr); + print_track(free_track, "Freed", false); pr_err("\n"); +#ifdef CONFIG_KASAN_RCU_STACK_RECORD + kasan_print_rcu_free_stack(alloc_info); +#endif } describe_object_addr(cache, object, addr); From patchwork Wed May 6 05:21:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Walter Wu X-Patchwork-Id: 11530227 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 71B531392 for ; Wed, 6 May 2020 05:22:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 31F1D20721 for ; Wed, 6 May 2020 05:22:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="s4FoA3LL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 31F1D20721 Authentication-Results: mail.kernel.org; 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Wed, 6 May 2020 13:21:55 +0800 From: Walter Wu To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Matthias Brugger CC: , , , , wsd_upstream , , Walter Wu Subject: [PATCH 2/3] kasan: record and print the free track Date: Wed, 6 May 2020 13:21:55 +0800 Message-ID: <20200506052155.14515-1-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: We add new KASAN_RCU_STACK_RECORD configuration option. It will move free track from slub meta-data (struct kasan_alloc_meta) into freed object. Because we hope this options doesn't enlarge slub meta-data size. This option doesn'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. This option is only suitable for generic KASAN, because we move free track into the freed object, so free track is valid information only when it exists in quarantine. If the object is in-use state, then the KASAN report doesn't print call_rcu() free track information. [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437 Signed-off-by: Walter Wu Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Alexander Potapenko --- mm/kasan/common.c | 10 +++++++++- mm/kasan/report.c | 24 +++++++++++++++++++++--- 2 files changed, 30 insertions(+), 4 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 32d422bdf127..13ec03e225a7 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -321,8 +321,15 @@ void kasan_record_callrcu(void *addr) /* record last call_rcu() call stack */ alloc_info->rcu_free_stack[1] = save_stack(GFP_NOWAIT); } -#endif +static void kasan_set_free_info(struct kmem_cache *cache, + void *object, u8 tag) +{ + /* store free track into freed object */ + set_track((struct kasan_track *)(object + BYTES_PER_WORD), GFP_NOWAIT); +} + +#else static void kasan_set_free_info(struct kmem_cache *cache, void *object, u8 tag) { @@ -339,6 +346,7 @@ static void kasan_set_free_info(struct kmem_cache *cache, set_track(&alloc_meta->free_track[idx], GFP_NOWAIT); } +#endif void kasan_poison_slab(struct page *page) { diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 7aaccc70b65b..f2b0c6b9dffa 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -175,8 +175,23 @@ static void kasan_print_rcu_free_stack(struct kasan_alloc_meta *alloc_info) print_track(&free_track, "Last call_rcu() call stack", true); pr_err("\n"); } -#endif +static 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 + BYTES_PER_WORD); + else + return NULL; +} + +#else static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, void *object, u8 tag, const void *addr) { @@ -196,6 +211,7 @@ static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, return &alloc_meta->free_track[i]; } +#endif static void describe_object(struct kmem_cache *cache, void *object, const void *addr, u8 tag) @@ -208,8 +224,10 @@ 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, addr); - print_track(free_track, "Freed", false); - pr_err("\n"); + if (free_track) { + print_track(free_track, "Freed", false); + pr_err("\n"); + } #ifdef CONFIG_KASAN_RCU_STACK_RECORD kasan_print_rcu_free_stack(alloc_info); #endif From patchwork Wed May 6 05:26:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Walter Wu X-Patchwork-Id: 11530233 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 92F4F14B4 for ; Wed, 6 May 2020 05:27:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 537BE20721 for ; 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Wed, 6 May 2020 13:26:55 +0800 From: Walter Wu To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Jonathan Corbet CC: , , , , wsd_upstream , , Walter Wu Subject: [PATCH 3/3] kasan: add KASAN_RCU_STACK_RECORD documentation Date: Wed, 6 May 2020 13:26:55 +0800 Message-ID: <20200506052655.14639-1-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 adds the documentation for the KASAN_RCU_STACK_RECORD config option. Signed-off-by: Walter Wu Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Jonathan Corbet --- Documentation/dev-tools/kasan.rst | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst index c652d740735d..368ff0dad0d7 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -281,3 +281,24 @@ unmapped. This will require changes in arch-specific code. This allows ``VMAP_STACK`` support on x86, and can simplify support of architectures that do not have a fixed module region. + +CONFIG_KASAN_RCU_STACK_RECORD +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +With CONFIG_KASAN_RCU_STACK_RECORD, when call_rcu() is called, it will +store the call_rcu() call stack into slub alloc meta-data. The goal +is to print call_rcu() information in KASAN report. It is helpful for +use-after-free or double free memory issue. + +Record first and last call_rcu() call stack and print two call_rcu() +call stack in KASAN report. + +This option doesn't increase the cost of memory consumption, we add two +call_rcu() call stack into struct kasan_alloc_meta and size is 8 bytes. +Remove the free track from struct kasan_alloc_meta and size is 8 bytes. +So we don't enlarge the slub meta-data size. + +This option is only suitable for generic KASAN. Because the free track +is stored in freed object. so free track is valid information only when +it exists in the quarantine. If the slub object is in-use state, then +KASAN report doesn't print call_rcu() free track information.