[PATCH] perf expr: Fix missing check for return value of hashmap__new

[PATCH] perf expr: Fix missing check for return value of hashmap__new

[Miaoqian Lin]

The hashmap__new() function may return ERR_PTR(-ENOMEM) when malloc
fails, add IS_ERR checking for ctx->ids.

Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
---
 tools/perf/util/expr.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index 1d532b9fed29..c94c9ea30d1a 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -299,6 +299,10 @@ struct expr_parse_ctx *expr__ctx_new(void)
 		return NULL;
 
 	ctx->ids = hashmap__new(key_hash, key_equal, NULL);
+	if (IS_ERR(ctx->ids)) {
+		kfree(ctx);
+		return NULL;
+	}
 	ctx->runtime = 0;
 
 	return ctx;
-- 
2.17.1

Re: [PATCH] perf expr: Fix missing check for return value of hashmap__new

[Arnaldo Carvalho de Melo]

Em Sun, Dec 12, 2021 at 06:25:02AM +0000, Miaoqian Lin escreveu:
> The hashmap__new() function may return ERR_PTR(-ENOMEM) when malloc
> fails, add IS_ERR checking for ctx->ids.
> 
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>

Thanks, applied.

As a follow up you may consider using ids__new() instead:

struct hashmap *ids__new(void)
{
        return hashmap__new(key_hash, key_equal, NULL);
}

And I noticed that the users of ids__new() are not using IS_ERR() on its
return in tools/perf/tests/expr.c, e.g.:

static int test_ids_union(void)
{
        struct hashmap *ids1, *ids2;

        /* Empty union. */
        ids1 = ids__new();
        TEST_ASSERT_VAL("ids__new", ids1);
        ids2 = ids__new();
        TEST_ASSERT_VAL("ids__new", ids2);

This needs converting to TEST_ASSERT_VAL_IS_ERR() probably after
introducing it, I haven't checked if this variation exists.

- Arnaldo

> ---
>  tools/perf/util/expr.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
> index 1d532b9fed29..c94c9ea30d1a 100644
> --- a/tools/perf/util/expr.c
> +++ b/tools/perf/util/expr.c
> @@ -299,6 +299,10 @@ struct expr_parse_ctx *expr__ctx_new(void)
>  		return NULL;
>  
>  	ctx->ids = hashmap__new(key_hash, key_equal, NULL);
> +	if (IS_ERR(ctx->ids)) {
> +		kfree(ctx);
> +		return NULL;
> +	}
>  	ctx->runtime = 0;
>  
>  	return ctx;
> -- 
> 2.17.1

-- 

- Arnaldo

Re: [PATCH] perf expr: Fix missing check for return value of hashmap__new

[Arnaldo Carvalho de Melo]

Em Mon, Dec 13, 2021 at 10:06:02AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Sun, Dec 12, 2021 at 06:25:02AM +0000, Miaoqian Lin escreveu:
> > The hashmap__new() function may return ERR_PTR(-ENOMEM) when malloc
> > fails, add IS_ERR checking for ctx->ids.
> > 
> > Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
> 
> Thanks, applied.

I take that back, kfree()? Are you compile testing this?

  CC      /tmp/build/perf/util/expr.o
util/expr.c: In function ‘expr__ctx_new’:
util/expr.c:302:13: error: implicit declaration of function ‘IS_ERR’ [-Werror=implicit-function-declaration]
  302 |         if (IS_ERR(ctx->ids)) {
      |             ^~~~~~
util/expr.c:303:17: error: implicit declaration of function ‘kfree’; did you mean ‘free’? [-Werror=implicit-function-declaration]
  303 |                 kfree(ctx);
      |                 ^~~~~
      |                 free
cc1: all warnings being treated as errors

I had to fix it applying this on top, please compile test your patches.

- Arnaldo

diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index c94c9ea30d1abd6a..254601060b392c42 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -12,6 +12,7 @@
 #include "expr-bison.h"
 #include "expr-flex.h"
 #include "smt.h"
+#include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/zalloc.h>
 #include <ctype.h>
@@ -300,7 +301,7 @@ struct expr_parse_ctx *expr__ctx_new(void)
 
 	ctx->ids = hashmap__new(key_hash, key_equal, NULL);
 	if (IS_ERR(ctx->ids)) {
-		kfree(ctx);
+		free(ctx);
 		return NULL;
 	}
 	ctx->runtime = 0;