perf tools: fix off-by-one error in maps

PATCH Superseded Stephane Eranian 3 participants 5 messages Oct 3, 2014 – Oct 6, 2014 perf events

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Stephane Eranian

author

2014-10-03 10:47 UTC #0 lore raw

PATCH 1/1 perf tools: fix off-by-one error in maps

This patch fixes off-by-one errors in the management of maps. A map is defined by start address and length as implemented by map__new():

map__init(map, type, start, start + len, pgoff, dso);

map__init()
{
map->start = addr;
map->end = end;
}

Consequently, the actual address range is ]start; end[ map->end is the first byte outside the range. This patch fixes two bugs where upper bounds were off-by-one.

Signed-off-by Stephane Eranian <[email protected]>

tools/perf/util/map.c +2 -2

index b709059..9e2c71e 100644
@@ -556,7 +556,7 @@ struct symbol *map_groups__find_symbol_by_name(struct map_groups *mg,
 
 int map_groups__find_ams(struct addr_map_symbol *ams, symbol_filter_t filter)
 {
-	if (ams->addr < ams->map->start || ams->addr > ams->map->end) {
+	if (ams->addr < ams->map->start || ams->addr >= ams->map->end) {
 		if (ams->map->groups == NULL)
 			return -1;
 		ams->map = map_groups__find(ams->map->groups, ams->map->type,

@@ -678,7 +678,7 @@ int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map,
 				goto move_map;
 			}
 
-			after->start = map->end + 1;
+			after->start = map->end;
 			map_groups__insert(mg, after);
 			if (verbose >= 2)
 				map__fprintf(after, fp);

Jiri Olsa

2014-10-05 19:23 UTC #1 lore raw

Quoted 1 line · Stephane Eranian

SNIP

Quoted 16 lines

Signed-off-by Stephane Eranian <[email protected]>

tools/perf/util/map.c +1 -1

index b709059..9e2c71e 100644
@@ -556,7 +556,7 @@ struct symbol *map_groups__find_symbol_by_name(struct map_groups *mg,
 
 int map_groups__find_ams(struct addr_map_symbol *ams, symbol_filter_t filter)
 {
-	if (ams->addr < ams->map->start || ams->addr > ams->map->end) {
+	if (ams->addr < ams->map->start || ams->addr >= ams->map->end) {
 		if (ams->map->groups == NULL)
 			return -1;
 		ams->map = map_groups__find(ams->map->groups, ams->map->type,

tools/perf/util/map.c int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map, · line 684

Quoted 8 lines

tools/perf/util/map.c +1 -1

@@ -678,7 +678,7 @@ int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map,
 				goto move_map;
 			}
 
-			after->start = map->end + 1;
+			after->start = map->end;
 			map_groups__insert(mg, after);
 			if (verbose >= 2)
 				map__fprintf(after, fp);

hum, do we also need this one then?

---

tools/perf/util/map.c +1 -1

index 9e2c71e51fce..186418ba18db 100644
@@ -664,7 +664,7 @@ int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map,
 				goto move_map;
 			}
 
-			before->end = map->start - 1;
+			before->end = map->start;
 			map_groups__insert(mg, before);
 			if (verbose >= 2)
 				map__fprintf(before, fp);

Stephane Eranian

author

2014-10-05 19:44 UTC #2 lore raw

Quoted 38 lines · Jiri Olsa

Quoted 1 line · Stephane Eranian

SNIP

Quoted 16 lines

Signed-off-by Stephane Eranian <[email protected]>

tools/perf/util/map.c +1 -1

index b709059..9e2c71e 100644
@@ -556,7 +556,7 @@ struct symbol *map_groups__find_symbol_by_name(struct map_groups *mg,
 
 int map_groups__find_ams(struct addr_map_symbol *ams, symbol_filter_t filter)
 {
-     if (ams->addr < ams->map->start || ams->addr > ams->map->end) {
+     if (ams->addr < ams->map->start || ams->addr >= ams->map->end) {
              if (ams->map->groups == NULL)
                      return -1;
              ams->map = map_groups__find(ams->map->groups, ams->map->type,

tools/perf/util/map.c int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map, · line 684

Quoted 8 lines

tools/perf/util/map.c +1 -1

@@ -678,7 +678,7 @@ int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map,
                              goto move_map;
                      }
 
-                     after->start = map->end + 1;
+                     after->start = map->end;
                      map_groups__insert(mg, after);
                      if (verbose >= 2)
                              map__fprintf(after, fp);

hum, do we also need this one then?

---

tools/perf/util/map.c +0 -0

index 9e2c71e51fce..186418ba18db 100644

tools/perf/util/map.c int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map, · line 667

Quoted 5 lines

tools/perf/util/map.c +1 -1

@@ -664,7 +664,7 @@ int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map,
                                goto move_map;
                        }
 
-                       before->end = map->start - 1;
+                       before->end = map->start;

Start is first byte of next range, so it is pointing to one byte after the end of the before range.
So, yes, I think we need your fix as well. I missed it. Will repost.

Quoted 3 lines

tools/perf/util/map.c +0 -0

                        map_groups__insert(mg, before);
                        if (verbose >= 2)
                                map__fprintf(before, fp);

Arnaldo Carvalho de Melo

2014-10-06 15:18 UTC #3 lore raw

In reply to Stephane Eranian

Em Fri, Oct 03, 2014 at 12:47:07PM +0200, Stephane Eranian escreveu:

Quoted 7 lines

This patch fixes off-by-one errors in the management of maps. A map is defined by start address and length as implemented by map__new():
map__init(map, type, start, start + len, pgoff, dso);

Quoted 8 lines

map__init()
{
map->start = addr;
map->end = end;
}
Consequently, the actual address range is ]start; end[ map->end is the first byte outside the range. This patch

I thought map->end should be the end of the range, not something after the end, is that really the case?

I.e. the bug would be in that call to map__init, that should instead be:

	map__init(map, type, start, start + len - 1, pgoff, dso);

no? Isn't that clearer, i.e. to keep the semantics of 'end'?

- Arnaldo

Quoted 26 lines

fixes two bugs where upper bounds were off-by-one.

Signed-off-by Stephane Eranian <[email protected]>

tools/perf/util/map.c +2 -2

index b709059..9e2c71e 100644
@@ -556,7 +556,7 @@ struct symbol *map_groups__find_symbol_by_name(struct map_groups *mg,
 
 int map_groups__find_ams(struct addr_map_symbol *ams, symbol_filter_t filter)
 {
-	if (ams->addr < ams->map->start || ams->addr > ams->map->end) {
+	if (ams->addr < ams->map->start || ams->addr >= ams->map->end) {
 		if (ams->map->groups == NULL)
 			return -1;
 		ams->map = map_groups__find(ams->map->groups, ams->map->type,

@@ -678,7 +678,7 @@ int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map,
 				goto move_map;
 			}
 
-			after->start = map->end + 1;
+			after->start = map->end;
 			map_groups__insert(mg, after);
 			if (verbose >= 2)
 				map__fprintf(after, fp);

Stephane Eranian

author

2014-10-06 19:57 UTC #4 lore raw

Arnaldo,

Quoted 14 lines · Arnaldo Carvalho de Melo

Em Fri, Oct 03, 2014 at 12:47:07PM +0200, Stephane Eranian escreveu:
Quoted 13 lines
This patch fixes off-by-one errors in the management of maps. A map is defined by start address and length as implemented by map__new():
map__init(map, type, start, start + len, pgoff, dso);
map__init()
{
map->start = addr;
map->end = end;
}

Quoted 6 lines

Quoted 2 lines
Consequently, the actual address range is ]start; end[ map->end is the first byte outside the range. This patch
I thought map->end should be the end of the range, not something after the end, is that really the case?

map->start = start;
map->end = start + len;

Thus map->end is the first byte after the end.

Quoted 3 lines

I.e. the bug would be in that call to map__init, that should instead be:
        map__init(map, type, start, start + len - 1, pgoff, dso);

Yeah, that is the alternative. But are you sure this is the only place where a map
is initialized. And this is not really C like.

Quoted 3 lines

no? Isn't that clearer, i.e. to keep the semantics of 'end'?

Yeah, it all depends on what you meant by end: last byte or first byte after. But then everything needs to be consistent. That is what I am trying to fix in this patch.

Quoted 28 lines

- Arnaldo

Quoted 26 lines

fixes two bugs where upper bounds were off-by-one.

Signed-off-by Stephane Eranian <[email protected]>

tools/perf/util/map.c +2 -2

index b709059..9e2c71e 100644
@@ -556,7 +556,7 @@ struct symbol *map_groups__find_symbol_by_name(struct map_groups *mg,
 
 int map_groups__find_ams(struct addr_map_symbol *ams, symbol_filter_t filter)
 {
-     if (ams->addr < ams->map->start || ams->addr > ams->map->end) {
+     if (ams->addr < ams->map->start || ams->addr >= ams->map->end) {
              if (ams->map->groups == NULL)
                      return -1;
              ams->map = map_groups__find(ams->map->groups, ams->map->type,

@@ -678,7 +678,7 @@ int map_groups__fixup_overlappings(struct map_groups *mg, struct map *map,
                              goto move_map;
                      }
 
-                     after->start = map->end + 1;
+                     after->start = map->end;
                      map_groups__insert(mg, after);
                      if (verbose >= 2)
                              map__fprintf(after, fp);