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authorAndrey Konovalov <andreyknvl@google.com>2018-12-28 11:30:42 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-28 23:11:44 +0300
commit121e8f81d38cc43834195722d0768340dc130a33 (patch)
tree32faed70e178a432765edf7e12ad3e8314db15f1 /mm
parent11cd3cd69a256a353dd1a249b48ccd727d945952 (diff)
downloadlinux-121e8f81d38cc43834195722d0768340dc130a33.tar.xz
kasan: add bug reporting routines for tag-based mode
This commit adds rountines, that print tag-based KASAN error reports. Those are quite similar to generic KASAN, the difference is: 1. The way tag-based KASAN finds the first bad shadow cell (with a mismatching tag). Tag-based KASAN compares memory tags from the shadow memory to the pointer tag. 2. Tag-based KASAN reports all bugs with the "KASAN: invalid-access" header. Also simplify generic KASAN find_first_bad_addr. Link: http://lkml.kernel.org/r/aee6897b1bd077732a315fd84c6b4f234dbfdfcb.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/kasan/generic_report.c16
-rw-r--r--mm/kasan/kasan.h5
-rw-r--r--mm/kasan/report.c57
-rw-r--r--mm/kasan/tags_report.c18
4 files changed, 59 insertions, 37 deletions
diff --git a/mm/kasan/generic_report.c b/mm/kasan/generic_report.c
index 5201d1770700..a4604cceae59 100644
--- a/mm/kasan/generic_report.c
+++ b/mm/kasan/generic_report.c
@@ -33,16 +33,13 @@
#include "kasan.h"
#include "../slab.h"
-static const void *find_first_bad_addr(const void *addr, size_t size)
+void *find_first_bad_addr(void *addr, size_t size)
{
- u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
- const void *first_bad_addr = addr;
+ void *p = addr;
- while (!shadow_val && first_bad_addr < addr + size) {
- first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
- shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
- }
- return first_bad_addr;
+ while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
+ p += KASAN_SHADOW_SCALE_SIZE;
+ return p;
}
static const char *get_shadow_bug_type(struct kasan_access_info *info)
@@ -50,9 +47,6 @@ static const char *get_shadow_bug_type(struct kasan_access_info *info)
const char *bug_type = "unknown-crash";
u8 *shadow_addr;
- info->first_bad_addr = find_first_bad_addr(info->access_addr,
- info->access_size);
-
shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
/*
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 33cc3b0e017e..82a23b23ff93 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -119,6 +119,7 @@ void kasan_poison_shadow(const void *address, size_t size, u8 value);
void check_memory_region(unsigned long addr, size_t size, bool write,
unsigned long ret_ip);
+void *find_first_bad_addr(void *addr, size_t size);
const char *get_bug_type(struct kasan_access_info *info);
void kasan_report(unsigned long addr, size_t size,
@@ -139,10 +140,14 @@ static inline void quarantine_remove_cache(struct kmem_cache *cache) { }
#ifdef CONFIG_KASAN_SW_TAGS
+void print_tags(u8 addr_tag, const void *addr);
+
u8 random_tag(void);
#else
+static inline void print_tags(u8 addr_tag, const void *addr) { }
+
static inline u8 random_tag(void)
{
return 0;
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 64a74f334c45..214d85035f99 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -64,11 +64,10 @@ static int __init kasan_set_multi_shot(char *str)
}
__setup("kasan_multi_shot", kasan_set_multi_shot);
-static void print_error_description(struct kasan_access_info *info,
- const char *bug_type)
+static void print_error_description(struct kasan_access_info *info)
{
pr_err("BUG: KASAN: %s in %pS\n",
- bug_type, (void *)info->ip);
+ get_bug_type(info), (void *)info->ip);
pr_err("%s of size %zu at addr %px by task %s/%d\n",
info->is_write ? "Write" : "Read", info->access_size,
info->access_addr, current->comm, task_pid_nr(current));
@@ -272,6 +271,8 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
start_report(&flags);
pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
+ print_tags(get_tag(object), reset_tag(object));
+ object = reset_tag(object);
pr_err("\n");
print_address_description(object);
pr_err("\n");
@@ -279,41 +280,45 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
end_report(&flags);
}
-static void kasan_report_error(struct kasan_access_info *info)
-{
- unsigned long flags;
-
- start_report(&flags);
-
- print_error_description(info, get_bug_type(info));
- pr_err("\n");
-
- if (!addr_has_shadow(info->access_addr)) {
- dump_stack();
- } else {
- print_address_description((void *)info->access_addr);
- pr_err("\n");
- print_shadow_for_address(info->first_bad_addr);
- }
-
- end_report(&flags);
-}
-
void kasan_report(unsigned long addr, size_t size,
bool is_write, unsigned long ip)
{
struct kasan_access_info info;
+ void *tagged_addr;
+ void *untagged_addr;
+ unsigned long flags;
if (likely(!report_enabled()))
return;
disable_trace_on_warning();
- info.access_addr = (void *)addr;
- info.first_bad_addr = (void *)addr;
+ tagged_addr = (void *)addr;
+ untagged_addr = reset_tag(tagged_addr);
+
+ info.access_addr = tagged_addr;
+ if (addr_has_shadow(untagged_addr))
+ info.first_bad_addr = find_first_bad_addr(tagged_addr, size);
+ else
+ info.first_bad_addr = untagged_addr;
info.access_size = size;
info.is_write = is_write;
info.ip = ip;
- kasan_report_error(&info);
+ start_report(&flags);
+
+ print_error_description(&info);
+ if (addr_has_shadow(untagged_addr))
+ print_tags(get_tag(tagged_addr), info.first_bad_addr);
+ pr_err("\n");
+
+ if (addr_has_shadow(untagged_addr)) {
+ print_address_description(untagged_addr);
+ pr_err("\n");
+ print_shadow_for_address(info.first_bad_addr);
+ } else {
+ dump_stack();
+ }
+
+ end_report(&flags);
}
diff --git a/mm/kasan/tags_report.c b/mm/kasan/tags_report.c
index 8af15e87d3bc..573c51d20d09 100644
--- a/mm/kasan/tags_report.c
+++ b/mm/kasan/tags_report.c
@@ -37,3 +37,21 @@ const char *get_bug_type(struct kasan_access_info *info)
{
return "invalid-access";
}
+
+void *find_first_bad_addr(void *addr, size_t size)
+{
+ u8 tag = get_tag(addr);
+ void *p = reset_tag(addr);
+ void *end = p + size;
+
+ while (p < end && tag == *(u8 *)kasan_mem_to_shadow(p))
+ p += KASAN_SHADOW_SCALE_SIZE;
+ return p;
+}
+
+void print_tags(u8 addr_tag, const void *addr)
+{
+ u8 *shadow = (u8 *)kasan_mem_to_shadow(addr);
+
+ pr_err("Pointer tag: [%02x], memory tag: [%02x]\n", addr_tag, *shadow);
+}