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Thu, 01 Oct 2020 10:44:05 -0700 (PDT) Date: Thu, 1 Oct 2020 19:43:59 +0200 From: elver@google.com To: Andrey Konovalov Cc: Dmitry Vyukov , Vincenzo Frascino , Catalin Marinas , kasan-dev@googlegroups.com, Andrey Ryabinin , Alexander Potapenko , Evgenii Stepanov , Elena Petrova , Branislav Rankov , Kevin Brodsky , Will Deacon , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 13/39] kasan: decode stack frame only with KASAN_STACK_ENABLE Message-ID: <20201001174359.GK4162920@elver.google.com> References: <4f2a790cc95d2ab6400e5f75fa78ff0a0fdd9593.1600987622.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4f2a790cc95d2ab6400e5f75fa78ff0a0fdd9593.1600987622.git.andreyknvl@google.com> User-Agent: Mutt/1.14.5 (2020-06-23) 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: On Fri, Sep 25, 2020 at 12:50AM +0200, Andrey Konovalov wrote: > Decoding routines aren't needed when CONFIG_KASAN_STACK_ENABLE is not > enabled. Currently only generic KASAN mode implements stack error > reporting. > > No functional changes for software modes. > > Signed-off-by: Andrey Konovalov > Signed-off-by: Vincenzo Frascino Reviewed-by: Marco Elver > --- > Change-Id: I084e3214f2b40dc0bef7c5a9fafdc6f5c42b06a2 > --- > mm/kasan/kasan.h | 6 ++ > mm/kasan/report.c | 162 -------------------------------------- > mm/kasan/report_generic.c | 161 +++++++++++++++++++++++++++++++++++++ > 3 files changed, 167 insertions(+), 162 deletions(-) > > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index 3eff57e71ff5..8dfacc0f73ea 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -169,6 +169,12 @@ bool check_invalid_free(void *addr); > void *find_first_bad_addr(void *addr, size_t size); > const char *get_bug_type(struct kasan_access_info *info); > > +#ifdef CONFIG_KASAN_STACK_ENABLE > +void print_address_stack_frame(const void *addr); > +#else > +static inline void print_address_stack_frame(const void *addr) { } > +#endif > + > bool kasan_report(unsigned long addr, size_t size, > bool is_write, unsigned long ip); > void kasan_report_invalid_free(void *object, unsigned long ip); > diff --git a/mm/kasan/report.c b/mm/kasan/report.c > index 5961dbfba080..f28eec5acdf6 100644 > --- a/mm/kasan/report.c > +++ b/mm/kasan/report.c > @@ -209,168 +209,6 @@ static inline bool init_task_stack_addr(const void *addr) > sizeof(init_thread_union.stack)); > } > > -static bool __must_check tokenize_frame_descr(const char **frame_descr, > - char *token, size_t max_tok_len, > - unsigned long *value) > -{ > - const char *sep = strchr(*frame_descr, ' '); > - > - if (sep == NULL) > - sep = *frame_descr + strlen(*frame_descr); > - > - if (token != NULL) { > - const size_t tok_len = sep - *frame_descr; > - > - if (tok_len + 1 > max_tok_len) { > - pr_err("KASAN internal error: frame description too long: %s\n", > - *frame_descr); > - return false; > - } > - > - /* Copy token (+ 1 byte for '\0'). */ > - strlcpy(token, *frame_descr, tok_len + 1); > - } > - > - /* Advance frame_descr past separator. */ > - *frame_descr = sep + 1; > - > - if (value != NULL && kstrtoul(token, 10, value)) { > - pr_err("KASAN internal error: not a valid number: %s\n", token); > - return false; > - } > - > - return true; > -} > - > -static void print_decoded_frame_descr(const char *frame_descr) > -{ > - /* > - * We need to parse the following string: > - * "n alloc_1 alloc_2 ... alloc_n" > - * where alloc_i looks like > - * "offset size len name" > - * or "offset size len name:line". > - */ > - > - char token[64]; > - unsigned long num_objects; > - > - if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > - &num_objects)) > - return; > - > - pr_err("\n"); > - pr_err("this frame has %lu %s:\n", num_objects, > - num_objects == 1 ? "object" : "objects"); > - > - while (num_objects--) { > - unsigned long offset; > - unsigned long size; > - > - /* access offset */ > - if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > - &offset)) > - return; > - /* access size */ > - if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > - &size)) > - return; > - /* name length (unused) */ > - if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL)) > - return; > - /* object name */ > - if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > - NULL)) > - return; > - > - /* Strip line number; without filename it's not very helpful. */ > - strreplace(token, ':', '\0'); > - > - /* Finally, print object information. */ > - pr_err(" [%lu, %lu) '%s'", offset, offset + size, token); > - } > -} > - > -static bool __must_check get_address_stack_frame_info(const void *addr, > - unsigned long *offset, > - const char **frame_descr, > - const void **frame_pc) > -{ > - unsigned long aligned_addr; > - unsigned long mem_ptr; > - const u8 *shadow_bottom; > - const u8 *shadow_ptr; > - const unsigned long *frame; > - > - BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP)); > - > - /* > - * NOTE: We currently only support printing frame information for > - * accesses to the task's own stack. > - */ > - if (!object_is_on_stack(addr)) > - return false; > - > - aligned_addr = round_down((unsigned long)addr, sizeof(long)); > - mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE); > - shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr); > - shadow_bottom = kasan_mem_to_shadow(end_of_stack(current)); > - > - while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) { > - shadow_ptr--; > - mem_ptr -= KASAN_GRANULE_SIZE; > - } > - > - while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) { > - shadow_ptr--; > - mem_ptr -= KASAN_GRANULE_SIZE; > - } > - > - if (shadow_ptr < shadow_bottom) > - return false; > - > - frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE); > - if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) { > - pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n", > - frame[0]); > - return false; > - } > - > - *offset = (unsigned long)addr - (unsigned long)frame; > - *frame_descr = (const char *)frame[1]; > - *frame_pc = (void *)frame[2]; > - > - return true; > -} > - > -static void print_address_stack_frame(const void *addr) > -{ > - unsigned long offset; > - const char *frame_descr; > - const void *frame_pc; > - > - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) > - return; > - > - if (!get_address_stack_frame_info(addr, &offset, &frame_descr, > - &frame_pc)) > - return; > - > - /* > - * get_address_stack_frame_info only returns true if the given addr is > - * on the current task's stack. > - */ > - pr_err("\n"); > - pr_err("addr %px is located in stack of task %s/%d at offset %lu in frame:\n", > - addr, current->comm, task_pid_nr(current), offset); > - pr_err(" %pS\n", frame_pc); > - > - if (!frame_descr) > - return; > - > - print_decoded_frame_descr(frame_descr); > -} > - > static void print_address_description(void *addr, u8 tag) > { > struct page *page = kasan_addr_to_page(addr); > diff --git a/mm/kasan/report_generic.c b/mm/kasan/report_generic.c > index 7d5b9e5c7cfe..42b2b5791733 100644 > --- a/mm/kasan/report_generic.c > +++ b/mm/kasan/report_generic.c > @@ -122,6 +122,167 @@ const char *get_bug_type(struct kasan_access_info *info) > return get_wild_bug_type(info); > } > > +#ifdef CONFIG_KASAN_STACK_ENABLE > +static bool __must_check tokenize_frame_descr(const char **frame_descr, > + char *token, size_t max_tok_len, > + unsigned long *value) > +{ > + const char *sep = strchr(*frame_descr, ' '); > + > + if (sep == NULL) > + sep = *frame_descr + strlen(*frame_descr); > + > + if (token != NULL) { > + const size_t tok_len = sep - *frame_descr; > + > + if (tok_len + 1 > max_tok_len) { > + pr_err("KASAN internal error: frame description too long: %s\n", > + *frame_descr); > + return false; > + } > + > + /* Copy token (+ 1 byte for '\0'). */ > + strlcpy(token, *frame_descr, tok_len + 1); > + } > + > + /* Advance frame_descr past separator. */ > + *frame_descr = sep + 1; > + > + if (value != NULL && kstrtoul(token, 10, value)) { > + pr_err("KASAN internal error: not a valid number: %s\n", token); > + return false; > + } > + > + return true; > +} > + > +static void print_decoded_frame_descr(const char *frame_descr) > +{ > + /* > + * We need to parse the following string: > + * "n alloc_1 alloc_2 ... alloc_n" > + * where alloc_i looks like > + * "offset size len name" > + * or "offset size len name:line". > + */ > + > + char token[64]; > + unsigned long num_objects; > + > + if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > + &num_objects)) > + return; > + > + pr_err("\n"); > + pr_err("this frame has %lu %s:\n", num_objects, > + num_objects == 1 ? "object" : "objects"); > + > + while (num_objects--) { > + unsigned long offset; > + unsigned long size; > + > + /* access offset */ > + if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > + &offset)) > + return; > + /* access size */ > + if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > + &size)) > + return; > + /* name length (unused) */ > + if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL)) > + return; > + /* object name */ > + if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > + NULL)) > + return; > + > + /* Strip line number; without filename it's not very helpful. */ > + strreplace(token, ':', '\0'); > + > + /* Finally, print object information. */ > + pr_err(" [%lu, %lu) '%s'", offset, offset + size, token); > + } > +} > + > +static bool __must_check get_address_stack_frame_info(const void *addr, > + unsigned long *offset, > + const char **frame_descr, > + const void **frame_pc) > +{ > + unsigned long aligned_addr; > + unsigned long mem_ptr; > + const u8 *shadow_bottom; > + const u8 *shadow_ptr; > + const unsigned long *frame; > + > + BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP)); > + > + /* > + * NOTE: We currently only support printing frame information for > + * accesses to the task's own stack. > + */ > + if (!object_is_on_stack(addr)) > + return false; > + > + aligned_addr = round_down((unsigned long)addr, sizeof(long)); > + mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE); > + shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr); > + shadow_bottom = kasan_mem_to_shadow(end_of_stack(current)); > + > + while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) { > + shadow_ptr--; > + mem_ptr -= KASAN_GRANULE_SIZE; > + } > + > + while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) { > + shadow_ptr--; > + mem_ptr -= KASAN_GRANULE_SIZE; > + } > + > + if (shadow_ptr < shadow_bottom) > + return false; > + > + frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE); > + if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) { > + pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n", > + frame[0]); > + return false; > + } > + > + *offset = (unsigned long)addr - (unsigned long)frame; > + *frame_descr = (const char *)frame[1]; > + *frame_pc = (void *)frame[2]; > + > + return true; > +} > + > +void print_address_stack_frame(const void *addr) > +{ > + unsigned long offset; > + const char *frame_descr; > + const void *frame_pc; > + > + if (!get_address_stack_frame_info(addr, &offset, &frame_descr, > + &frame_pc)) > + return; > + > + /* > + * get_address_stack_frame_info only returns true if the given addr is > + * on the current task's stack. > + */ > + pr_err("\n"); > + pr_err("addr %px is located in stack of task %s/%d at offset %lu in frame:\n", > + addr, current->comm, task_pid_nr(current), offset); > + pr_err(" %pS\n", frame_pc); > + > + if (!frame_descr) > + return; > + > + print_decoded_frame_descr(frame_descr); > +} > +#endif /* CONFIG_KASAN_STACK_ENABLE */ > + > #define DEFINE_ASAN_REPORT_LOAD(size) \ > void __asan_report_load##size##_noabort(unsigned long addr) \ > { \ > -- > 2.28.0.681.g6f77f65b4e-goog >