On Tue, 26 Oct 2021 at 13:52, Ondrej Mosnacek <omosnace@xxxxxxxxxx> wrote:
>
> Use the __selinux_once() macro to ensure that threads don't race to
> initialize the list of customizable types.
>
> Reported-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
> Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
> ---
> libselinux/src/is_customizable_type.c | 23 +++++++++++------------
> 1 file changed, 11 insertions(+), 12 deletions(-)
>
Tested-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
Found no further thread sanitizer issues while testing.
> diff --git a/libselinux/src/is_customizable_type.c b/libselinux/src/is_customizable_type.c
> index 1b17860c..f83e1e83 100644
> --- a/libselinux/src/is_customizable_type.c
> +++ b/libselinux/src/is_customizable_type.c
> @@ -9,7 +9,10 @@
> #include "selinux_internal.h"
> #include "context_internal.h"
>
> -static int get_customizable_type_list(char *** retlist)
> +static char **customizable_list = NULL;
> +static pthread_once_t customizable_once = PTHREAD_ONCE_INIT;
> +
> +static void customizable_init(void)
> {
> FILE *fp;
> char *buf;
> @@ -18,12 +21,12 @@ static int get_customizable_type_list(char *** retlist)
>
> fp = fopen(selinux_customizable_types_path(), "re");
> if (!fp)
> - return -1;
> + return;
>
> buf = malloc(selinux_page_size);
> if (!buf) {
> fclose(fp);
> - return -1;
> + return;
> }
> while (fgets_unlocked(buf, selinux_page_size, fp) && ctr < UINT_MAX) {
> ctr++;
> @@ -54,23 +57,19 @@ static int get_customizable_type_list(char *** retlist)
> fclose(fp);
> free(buf);
> if (!list)
> - return -1;
> - *retlist = list;
> - return 0;
> + return;
> + customizable_list = list;
> }
>
> -static char **customizable_list = NULL;
> -
> int is_context_customizable(const char * scontext)
> {
> int i;
> const char *type;
> context_t c;
>
> - if (!customizable_list) {
> - if (get_customizable_type_list(&customizable_list) != 0)
> - return -1;
> - }
> + __selinux_once(customizable_once, customizable_init);
> + if (!customizable_list)
> + return -1;
>
> c = context_new(scontext);
> if (!c)
> --
> 2.31.1
>
