On Tue, Feb 22, 2022 at 10:36 AM Christian Göttsche
<cgzones@xxxxxxxxxxxxxx> wrote:
>
> On the first loop iteration the variables `r_buf` and `reason_buf_used`
> are NULL respective 0. Please UBSAN by not adding them but instead
> directly assign NULL.
>
> services.c:800:16: runtime error: applying zero offset to null pointer
> #0 0x4d4fce in constraint_expr_eval_reason ./libsepol/src/services.c:800:16
> #1 0x4cf31a in sepol_validate_transition_reason_buffer ./libsepol/src/services.c:1079:8
>
> Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
Acked-by: James Carter <jwcart2@xxxxxxxxx>
> ---
> libsepol/src/services.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libsepol/src/services.c b/libsepol/src/services.c
> index 7becfd1b..29723729 100644
> --- a/libsepol/src/services.c
> +++ b/libsepol/src/services.c
> @@ -797,7 +797,7 @@ mls_ops:
>
> for (x = 0; buffers[x] != NULL; x++) {
> while (1) {
> - p = *r_buf + reason_buf_used;
> + p = *r_buf ? (*r_buf + reason_buf_used) : NULL;
> len = snprintf(p, reason_buf_len - reason_buf_used,
> "%s", buffers[x]);
> if (len < 0 || len >= reason_buf_len - reason_buf_used) {
> --
> 2.35.1
>
