perf disasm: Fix potential use-after-free on fileloc

The fileloc is a copy of a pointer to a string but in places like
symbol_disassemble__llvm this string appears to be freed setting up
potential use-after-frees:

llvm.c:
```
		dl = disasm_line__new(args);
		if (dl == NULL)
			goto err;

		annotation_line__add(&dl->al, &notes->src->source);

		free(args->fileloc);
```

disasm.c:
```
static void annotation_line__init(struct annotation_line *al,
				  struct annotate_args *args,
				  int nr)
{
	al->offset = args->offset;
	al->line = strdup(args->line);
	al->line_nr = args->line_nr;
	al->fileloc = args->fileloc;
	al->data_nr = nr;
}

struct disasm_line *disasm_line__new(struct annotate_args *args)
{
	struct disasm_line *dl = NULL;
	struct annotation *notes = symbol__annotation(args->ms->sym);
	int nr = notes->src->nr_events;

	dl = zalloc(disasm_line_size(nr));
	if (!dl)
		return NULL;

	annotation_line__init(&dl->al, args, nr);
```

Fix this by making the fileloc a copy of the underlying string in its
init/exit.

Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index ddcc488f2e5f0e5ce10dca8f98d60b8dc4b42fe8..3fcb3634a7e0301240199db7857e03fbd8f2db1a 100644 (file)
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -908,13 +908,14 @@ static void annotation_line__init(struct annotation_line *al,
        al->offset = args->offset;
        al->line = strdup(args->line);
        al->line_nr = args->line_nr;
-       al->fileloc = args->fileloc;
+       al->fileloc = args->fileloc ? strdup(args->fileloc) : NULL;
        al->data_nr = nr;
 }
 
 static void annotation_line__exit(struct annotation_line *al)
 {
        zfree_srcline(&al->path);
+       zfree(&al->fileloc);
        zfree(&al->line);
        zfree(&al->cycles);
        zfree(&al->br_cntr);
@@ -950,7 +951,7 @@ struct disasm_line *disasm_line__new(struct annotate_args *args)
 
        annotation_line__init(&dl->al, args, nr);
        if (dl->al.line == NULL)
-               goto out_delete;
+               goto out_free_line;
 
        if (args->offset != -1) {
                if (arch__is_powerpc(args->arch)) {
@@ -965,8 +966,7 @@ struct disasm_line *disasm_line__new(struct annotate_args *args)
        return dl;
 
 out_free_line:
-       zfree(&dl->al.line);
-out_delete:
+       annotation_line__exit(&dl->al);
        free(dl);
        return NULL;
 }