[hackers] [libgrapheme] Prevent two theoretical null-pointer-dereferences in gen/util.c || Laslo Hunhold

[git]

commit 558b9cc3bc6961d26104cf726fe148f58ba36940
Author:     Laslo Hunhold <d...@frign.de>
AuthorDate: Sun Nov 13 09:12:25 2022 +0100
Commit:     Laslo Hunhold <d...@frign.de>
CommitDate: Sun Nov 13 09:12:25 2022 +0100

    Prevent two theoretical null-pointer-dereferences in gen/util.c
    
    This was found using static analysis and is not a security issue given
    this is in the generating code, so no runtime-affection. The worst that
    could've happened beforehand is that the generating code segfaults and
    produces garbage tables which would lead to compilation failure.
    
    Signed-off-by: Laslo Hunhold <d...@frign.de>

diff --git a/gen/util.c b/gen/util.c
index ee36fa3..01d42db 100644
--- a/gen/util.c
+++ b/gen/util.c
@@ -602,7 +602,7 @@ properties_generate_break_property(const struct 
property_spec *spec,
 
 static int
 break_test_callback(const char *fname, char **field, size_t nfields,
-                      char *comment, void *payload)
+                    char *comment, void *payload)
 {
        struct break_test *t,
                **test = ((struct break_test_payload *)payload)->test;
@@ -668,7 +668,7 @@ break_test_callback(const char *fname, char **field, size_t 
nfields,
                        }
                }
        }
-       if (t->len[t->lenlen - 1] == 0) {
+       if (t->lenlen > 0 && t->len[t->lenlen - 1] == 0) {
                /*
                 * we allocated one more length than we needed because
                 * the breakpoint was at the end
@@ -677,7 +677,8 @@ break_test_callback(const char *fname, char **field, size_t 
nfields,
        }
 
        /* store comment */
-       if (((*test)[*testlen - 1].descr = strdup(comment)) == NULL) {
+       if (comment != NULL &&
+           ((*test)[*testlen - 1].descr = strdup(comment)) == NULL) {
                fprintf(stderr, "break_test_callback: strdup: %s.\n",
                        strerror(errno));
                return 1;