Re: [dpdk-dev] [PATCH] eal/trace: fix coverity issues

[David Marchand <david.marchand@redhat.com>]

On Mon, Apr 27, 2020 at 2:04 PM Sunil Kumar Kori <skori@marvell.com> wrote:
>
> Pointer was being dereferenced without NULL checking.
>
> Coverity issue: 357768
>
> Fixes: 8c8066ea6a7b ("trace: add trace mode configuration parameter")
>
> Signed-off-by: Sunil Kumar Kori <skori@marvell.com>
> ---
>  lib/librte_eal/common/eal_common_trace_utils.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_eal/common/eal_common_trace_utils.c b/lib/librte_eal/common/eal_common_trace_utils.c
> index fce8892c3..119e97119 100644
> --- a/lib/librte_eal/common/eal_common_trace_utils.c
> +++ b/lib/librte_eal/common/eal_common_trace_utils.c
> @@ -227,15 +227,16 @@ int
>  eal_trace_mode_args_save(const char *optarg)
>  {
>         struct trace *trace = trace_obj_get();
> -       size_t len = strlen(optarg);
>         unsigned long tmp;
>         char *pattern;
> +       size_t len;
>
>         if (optarg == NULL) {
>                 trace_err("no optarg is passed");
>                 return -EINVAL;
>         }
>
> +       len = strlen(optarg);
>         if (len == 0) {
>                 trace_err("value is not provided with option");
>                 return -EINVAL;

I was looking at some gcc 10 complaints on string manipulation later
in eal_trace_dir_args_save().

https://build.opensuse.org/package/live_build_log/home:dmarchan:branches:home:bluca:dpdk/dpdk/Fedora_Rawhide/x86_64

[  126s]   CC rte_malloc.o
[  127s] /home/abuild/rpmbuild/BUILD/dpdk-1587835122.b13ace300/lib/librte_eal/common/eal_common_trace_utils.c:
In function 'eal_trace_dir_args_save':
[  127s] /home/abuild/rpmbuild/BUILD/dpdk-1587835122.b13ace300/lib/librte_eal/common/eal_common_trace_utils.c:290:24:
error: 'sprintf' may write a terminating nul past the end of the
destination [-Werror=format-overflow=]
[  127s]   290 |  sprintf(dir_path, "%s/", optarg);
[  127s]       |                        ^
[  127s] /home/abuild/rpmbuild/BUILD/dpdk-1587835122.b13ace300/lib/librte_eal/common/eal_common_trace_utils.c:290:2:
note: 'sprintf' output between 2 and 4097 bytes into a destination of
size 4096
[  127s]   290 |  sprintf(dir_path, "%s/", optarg);
[  127s]       |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[  127s] cc1: all warnings being treated as errors


Could we use asprintf in all this code and avoid malloc + sprintf ?


Something like the _untested_ snippet?

diff --git a/lib/librte_eal/common/eal_common_trace_utils.c
b/lib/librte_eal/common/eal_common_trace_utils.c
index fce8892c38..4769bade97 100644
--- a/lib/librte_eal/common/eal_common_trace_utils.c
+++ b/lib/librte_eal/common/eal_common_trace_utils.c
@@ -267,8 +267,7 @@ int
 eal_trace_dir_args_save(char const *optarg)
 {
        struct trace *trace = trace_obj_get();
-       uint32_t size = sizeof(trace->dir);
-       char *dir_path = NULL;
+       char *dir_path;
        int rc;

        if (optarg == NULL) {
@@ -276,19 +275,18 @@ eal_trace_dir_args_save(char const *optarg)
                return -EINVAL;
        }

-       if (strlen(optarg) >= size) {
-               trace_err("input string is too big");
-               return -ENAMETOOLONG;
-       }
-
-       dir_path = (char *)calloc(1, size);
-       if (dir_path == NULL) {
-               trace_err("fail to allocate memory");
+       rc = asprintf(&dir_path, "%s/", optarg);
+       if (rc == -1) {
+               trace_err("failed to copy directory: %s", strerror(errno));
                return -ENOMEM;
        }

-       sprintf(dir_path, "%s/", optarg);
-       rc = trace_dir_update(dir_path);
+       if ((size_t)rc >= sizeof(trace->dir)) {
+               trace_err("input string is too big");
+               rc = -ENAMETOOLONG;
+       } else {
+               rc = trace_dir_update(dir_path);
+       }

        free(dir_path);
        return rc;



-- 
David Marchand