[PATCH v8 14/43] kasan: decode stack frame only with KASAN_STACK_ENABLE

Andrey Konovalov
2020-11-04T23:21:52Z

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 <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Marco Elver <elver@google.com>
---
Change-Id: I084e3214f2b40dc0bef7c5a9fafdc6f5c42b06a2
---
mm/kasan/kasan.h | 6 ++
mm/kasan/report.c | 162 --------------------------------------
mm/kasan/report_generic.c | 162 ++++++++++++++++++++++++++++++++++++++
3 files changed, 168 insertions(+), 162 deletions(-)

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 3eff57e71ff5..d0cf61d4d70d 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);

+#if defined(CONFIG_KASAN_GENERIC) && CONFIG_KASAN_STACK
+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 fff0c7befbfe..b18d193f7f58 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -211,168 +211,6 @@ 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..b543a1ed6078 100644
--- a/mm/kasan/report_generic.c
+++ b/mm/kasan/report_generic.c
@@ -16,6 +16,7 @@
#include <linux/mm.h>
#include <linux/printk.h>
#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
#include <linux/slab.h>
#include <linux/stackdepot.h>
#include <linux/stacktrace.h>
@@ -122,6 +123,167 @@ const char *get_bug_type(struct kasan_access_info *info)
return get_wild_bug_type(info);
}

+#if CONFIG_KASAN_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;
+}
+
+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 */
+
#define DEFINE_ASAN_REPORT_LOAD(size) \
void __asan_report_load##size##_noabort(unsigned long addr) \
{ \
--
2.29.1.341.ge80a0c044ae-goog