Commit 5d4c6ac9 authored by Juntong Deng's avatar Juntong Deng Committed by Andrew Morton
Browse files

kasan: record and report more information 

Record and report more information to help us find the cause of the bug
and to help us correlate the error with other system events.

This patch adds recording and showing CPU number and timestamp at
allocation and free (controlled by CONFIG_KASAN_EXTRA_INFO).  The
timestamps in the report use the same format and source as printk.

Error occurrence timestamp is already implicit in the printk log, and CPU
number is already shown by dump_stack_lvl, so there is no need to add it.

In order to record CPU number and timestamp at allocation and free,
corresponding members need to be added to the relevant data structures,
which will lead to increased memory consumption.

In Generic KASAN, members are added to struct kasan_track.  Since in most
cases, alloc meta is stored in the redzone and free meta is stored in the
object or the redzone, memory consumption will not increase much.

In SW_TAGS KASAN and HW_TAGS KASAN, members are added to struct
kasan_stack_ring_entry.  Memory consumption increases as the size of
struct kasan_stack_ring_entry increases (this part of the memory is
allocated by memblock), but since this is configurable, it is up to the
user to choose.

Link: https://lkml.kernel.org/r/VI1P193MB0752BD991325D10E4AB1913599BDA@VI1P193MB0752.EURP193.PROD.OUTLOOK.COM


Signed-off-by: default avatarJuntong Deng <juntong.deng@outlook.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 73829b71

lib/Kconfig.kasan

+21 −0
Original line number Diff line number Diff line
@@ -207,4 +207,25 @@ config KASAN_MODULE_TEST 
	  A part of the KASAN test suite that is not integrated with KUnit.

	  Incompatible with Hardware Tag-Based KASAN.



config KASAN_EXTRA_INFO

	bool "Record and report more information"

	depends on KASAN

	help

	  Record and report more information to help us find the cause of the

	  bug and to help us correlate the error with other system events.



	  Currently, the CPU number and timestamp are additionally

	  recorded for each heap block at allocation and free time, and

	  8 bytes will be added to each metadata structure that records

	  allocation or free information.



	  In Generic KASAN, each kmalloc-8 and kmalloc-16 object will add

	  16 bytes of additional memory consumption, and each kmalloc-32

	  object will add 8 bytes of additional memory consumption, not

	  affecting other larger objects.



	  In SW_TAGS KASAN and HW_TAGS KASAN, depending on the stack_ring_size

	  boot parameter, it will add 8 * stack_ring_size bytes of additional

	  memory consumption.



endif # KASAN

mm/kasan/common.c

+8 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/module.h>

#include <linux/printk.h>

#include <linux/sched.h>

#include <linux/sched/clock.h>

#include <linux/sched/task_stack.h>

#include <linux/slab.h>

#include <linux/stackdepot.h>
@@ -49,6 +50,13 @@ depot_stack_handle_t kasan_save_stack(gfp_t flags, depot_flags_t depot_flags) 


void kasan_set_track(struct kasan_track *track, gfp_t flags)

{

#ifdef CONFIG_KASAN_EXTRA_INFO

	u32 cpu = raw_smp_processor_id();

	u64 ts_nsec = local_clock();



	track->cpu = cpu;

	track->timestamp = ts_nsec >> 3;

#endif /* CONFIG_KASAN_EXTRA_INFO */

	track->pid = current->pid;

	track->stack = kasan_save_stack(flags,

			STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET);

mm/kasan/kasan.h

+8 −0
Original line number Diff line number Diff line
@@ -187,6 +187,10 @@ static inline bool kasan_requires_meta(void) 
struct kasan_track {

	u32 pid;

	depot_stack_handle_t stack;

#ifdef CONFIG_KASAN_EXTRA_INFO

	u64 cpu:20;

	u64 timestamp:44;

#endif /* CONFIG_KASAN_EXTRA_INFO */

};



enum kasan_report_type {
@@ -278,6 +282,10 @@ struct kasan_stack_ring_entry { 
	u32 pid;

	depot_stack_handle_t stack;

	bool is_free;

#ifdef CONFIG_KASAN_EXTRA_INFO

	u64 cpu:20;

	u64 timestamp:44;

#endif /* CONFIG_KASAN_EXTRA_INFO */

};



struct kasan_stack_ring {

mm/kasan/report.c

+12 −0
Original line number Diff line number Diff line
@@ -262,7 +262,19 @@ static void print_error_description(struct kasan_report_info *info) 


static void print_track(struct kasan_track *track, const char *prefix)

{

#ifdef CONFIG_KASAN_EXTRA_INFO

	u64 ts_nsec = track->timestamp;

	unsigned long rem_usec;



	ts_nsec <<= 3;

	rem_usec = do_div(ts_nsec, NSEC_PER_SEC) / 1000;



	pr_err("%s by task %u on cpu %d at %lu.%06lus:\n",

			prefix, track->pid, track->cpu,

			(unsigned long)ts_nsec, rem_usec);

#else

	pr_err("%s by task %u:\n", prefix, track->pid);

#endif /* CONFIG_KASAN_EXTRA_INFO */

	if (track->stack)

		stack_depot_print(track->stack);

	else

mm/kasan/report_tags.c

+15 −0
Original line number Diff line number Diff line
@@ -27,6 +27,15 @@ static const char *get_common_bug_type(struct kasan_report_info *info) 
	return "invalid-access";

}



#ifdef CONFIG_KASAN_EXTRA_INFO

static void kasan_complete_extra_report_info(struct kasan_track *track,

					 struct kasan_stack_ring_entry *entry)

{

	track->cpu = entry->cpu;

	track->timestamp = entry->timestamp;

}

#endif /* CONFIG_KASAN_EXTRA_INFO */



void kasan_complete_mode_report_info(struct kasan_report_info *info)

{

	unsigned long flags;
@@ -73,6 +82,9 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info) 


			info->free_track.pid = entry->pid;

			info->free_track.stack = entry->stack;

#ifdef CONFIG_KASAN_EXTRA_INFO

			kasan_complete_extra_report_info(&info->free_track, entry);

#endif /* CONFIG_KASAN_EXTRA_INFO */

			free_found = true;



			/*
@@ -88,6 +100,9 @@ void kasan_complete_mode_report_info(struct kasan_report_info *info) 


			info->alloc_track.pid = entry->pid;

			info->alloc_track.stack = entry->stack;

#ifdef CONFIG_KASAN_EXTRA_INFO

			kasan_complete_extra_report_info(&info->alloc_track, entry);

#endif /* CONFIG_KASAN_EXTRA_INFO */

			alloc_found = true;



			/*