This commit adds rountines, that print KHWASAN error reports. Those are quite similar to KASAN, the difference is:
1. The way KHWASAN finds the first bad shadow cell (with a mismatching tag). KHWASAN compares memory tags from the shadow memory to the pointer tag. 2. KHWASAN reports all bugs with the "KASAN: invalid-access" header. This is done, so various external tools that already parse the kernel logs looking for KASAN reports wouldn't need to be changed. Signed-off-by: Andrey Konovalov <[email protected]> --- include/linux/kasan.h | 3 ++ mm/kasan/report.c | 88 ++++++++++++++++++++++++++++++++++++++----- 2 files changed, 82 insertions(+), 9 deletions(-) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index a2869464a8be..54e7c437dc8f 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -161,6 +161,9 @@ void *khwasan_set_tag(const void *addr, u8 tag); u8 khwasan_get_tag(const void *addr); void *khwasan_reset_tag(const void *ptr); +void khwasan_report(unsigned long addr, size_t size, bool write, + unsigned long ip); + #else /* CONFIG_KASAN_TAGS */ static inline void khwasan_init(void) { } diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 5c169aa688fd..ed17168a083e 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -51,10 +51,9 @@ static const void *find_first_bad_addr(const void *addr, size_t size) return first_bad_addr; } -static bool addr_has_shadow(struct kasan_access_info *info) +static bool addr_has_shadow(const void *addr) { - return (info->access_addr >= - kasan_shadow_to_mem((void *)KASAN_SHADOW_START)); + return (addr >= kasan_shadow_to_mem((void *)KASAN_SHADOW_START)); } static const char *get_shadow_bug_type(struct kasan_access_info *info) @@ -127,15 +126,14 @@ static const char *get_wild_bug_type(struct kasan_access_info *info) static const char *get_bug_type(struct kasan_access_info *info) { - if (addr_has_shadow(info)) + if (addr_has_shadow(info->access_addr)) return get_shadow_bug_type(info); return get_wild_bug_type(info); } -static void print_error_description(struct kasan_access_info *info) +static void print_error_description(struct kasan_access_info *info, + const char *bug_type) { - const char *bug_type = get_bug_type(info); - pr_err("BUG: KASAN: %s in %pS\n", bug_type, (void *)info->ip); pr_err("%s of size %zu at addr %px by task %s/%d\n", @@ -345,10 +343,10 @@ static void kasan_report_error(struct kasan_access_info *info) kasan_start_report(&flags); - print_error_description(info); + print_error_description(info, get_bug_type(info)); pr_err("\n"); - if (!addr_has_shadow(info)) { + if (!addr_has_shadow(info->access_addr)) { dump_stack(); } else { print_address_description((void *)info->access_addr); @@ -412,6 +410,78 @@ void kasan_report(unsigned long addr, size_t size, kasan_report_error(&info); } +static inline void khwasan_print_tags(const void *addr) +{ + u8 addr_tag = get_tag(addr); + void *untagged_addr = reset_tag(addr); + u8 *shadow = (u8 *)kasan_mem_to_shadow(untagged_addr); + + pr_err("Pointer tag: [%02x], memory tag: [%02x]\n", addr_tag, *shadow); +} + +static const void *khwasan_find_first_bad_addr(const void *addr, size_t size) +{ + u8 tag = get_tag((void *)addr); + void *untagged_addr = reset_tag((void *)addr); + u8 *shadow = (u8 *)kasan_mem_to_shadow(untagged_addr); + const void *first_bad_addr = untagged_addr; + + while (*shadow == tag && first_bad_addr < untagged_addr + size) { + first_bad_addr += KASAN_SHADOW_SCALE_SIZE; + shadow = (u8 *)kasan_mem_to_shadow(first_bad_addr); + } + return first_bad_addr; +} + +void khwasan_report(unsigned long addr, size_t size, bool write, + unsigned long ip) +{ + struct kasan_access_info info; + unsigned long flags; + void *untagged_addr = reset_tag((void *)addr); + + if (likely(!kasan_report_enabled())) + return; + + disable_trace_on_warning(); + + info.access_addr = (void *)addr; + info.first_bad_addr = khwasan_find_first_bad_addr((void *)addr, size); + info.access_size = size; + info.is_write = write; + info.ip = ip; + + kasan_start_report(&flags); + + print_error_description(&info, "invalid-access"); + khwasan_print_tags((void *)addr); + pr_err("\n"); + + if (!addr_has_shadow(untagged_addr)) { + dump_stack(); + } else { + print_address_description(untagged_addr); + pr_err("\n"); + print_shadow_for_address(info.first_bad_addr); + } + + kasan_end_report(&flags); +} + +void khwasan_report_invalid_free(void *object, unsigned long ip) +{ + unsigned long flags; + void *untagged_addr = reset_tag((void *)object); + + kasan_start_report(&flags); + pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip); + khwasan_print_tags(object); + pr_err("\n"); + print_address_description(untagged_addr); + pr_err("\n"); + print_shadow_for_address(untagged_addr); + kasan_end_report(&flags); +} #define DEFINE_ASAN_REPORT_LOAD(size) \ void __asan_report_load##size##_noabort(unsigned long addr) \ -- 2.17.0.rc0.231.g781580f067-goog _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
