parse-options: don't leak alias help messages

preprocess_options() allocates new strings for help messages for
OPTION_ALIAS. Therefore we also need to clean those help messages up
when freeing the returned options.

First introduced in:
  7c280589cf (parse-options: teach "git cmd -h" to show alias as alias, 2020-03-16)

The preprocessed options themselves no longer contain any indication
that a given option is/was an alias - therefore we add a new flag to
indicate former aliases. (An alternative approach would be to look back
at the original options to determine which options are aliases - but
that seems like a fragile approach. Or we could even look at the
alias_groups list - which might be less fragile, but would be slower
as it requires nested looping.)

As far as I can tell, parse_options() is only ever used once per
command, and the help messages are small - hence this leak has very
little impact.

This leak was found while running t0001. LSAN output can be found below:

Direct leak of 65 byte(s) in 1 object(s) allocated from:
    #0 0x49a859 in realloc /home/abuild/rpmbuild/BUILD/llvm-11.0.0.src/build/../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3
    #1 0x9aae36 in xrealloc /home/ahunt/oss-fuzz/git/wrapper.c:126:8
    #2 0x939d8d in strbuf_grow /home/ahunt/oss-fuzz/git/strbuf.c:98:2
    #3 0x93b936 in strbuf_vaddf /home/ahunt/oss-fuzz/git/strbuf.c:392:3
    #4 0x93b7ff in strbuf_addf /home/ahunt/oss-fuzz/git/strbuf.c:333:2
    #5 0x86747e in preprocess_options /home/ahunt/oss-fuzz/git/parse-options.c:666:3
    #6 0x866ed2 in parse_options /home/ahunt/oss-fuzz/git/parse-options.c:847:17
    #7 0x51c4a7 in cmd_clone /home/ahunt/oss-fuzz/git/builtin/clone.c:989:9
    #8 0x4cd60d in run_builtin /home/ahunt/oss-fuzz/git/git.c:453:11
    #9 0x4cb2da in handle_builtin /home/ahunt/oss-fuzz/git/git.c:704:3
    #10 0x4ccc37 in run_argv /home/ahunt/oss-fuzz/git/git.c:771:4
    #11 0x4cac29 in cmd_main /home/ahunt/oss-fuzz/git/git.c:902:19
    #12 0x69c9fe in main /home/ahunt/oss-fuzz/git/common-main.c:52:11
    #13 0x7fdac42d4349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Signed-off-by: Andrzej Hunt <ajrhunt@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/parse-options.c b/parse-options.c
index fbea16eaf5c2051f062bcf8b34ab99c3a4313075..e6f56768ca5de8f644143ee462ac11dd959e5946 100644 (file)
--- a/parse-options.c
+++ b/parse-options.c
@@ -625,6 +625,8 @@ static int show_gitcomp(const struct option *opts, int show_all)
  *
  * Right now this is only used to preprocess and substitute
  * OPTION_ALIAS.
+ *
+ * The returned options should be freed using free_preprocessed_options.
  */
 static struct option *preprocess_options(struct parse_opt_ctx_t *ctx,
                                         const struct option *options)
@@ -678,6 +680,7 @@ static struct option *preprocess_options(struct parse_opt_ctx_t *ctx,
                        newopt[i].short_name = short_name;
                        newopt[i].long_name = long_name;
                        newopt[i].help = strbuf_detach(&help, NULL);
+                       newopt[i].flags |= PARSE_OPT_FROM_ALIAS;
                        break;
                }
 
@@ -693,6 +696,20 @@ static struct option *preprocess_options(struct parse_opt_ctx_t *ctx,
        return newopt;
 }
 
+static void free_preprocessed_options(struct option *options)
+{
+       int i;
+
+       if (!options)
+               return;
+
+       for (i = 0; options[i].type != OPTION_END; i++) {
+               if (options[i].flags & PARSE_OPT_FROM_ALIAS)
+                       free((void *)options[i].help);
+       }
+       free(options);
+}
+
 static int usage_with_options_internal(struct parse_opt_ctx_t *,
                                       const char * const *,
                                       const struct option *, int, int);
@@ -870,7 +887,7 @@ int parse_options(int argc, const char **argv, const char *prefix,
        }
 
        precompose_argv_prefix(argc, argv, NULL);
-       free(real_options);
+       free_preprocessed_options(real_options);
        free(ctx.alias_groups);
        return parse_options_end(&ctx);
 }

diff --git a/parse-options.h b/parse-options.h
index f2ddef18f7b0b584a4ca3ac9ac4d19357717af93..a845a9d9527476fbe5269756a7fd03aed6c6d4d7 100644 (file)
--- a/parse-options.h
+++ b/parse-options.h
@@ -44,6 +44,7 @@ enum parse_opt_option_flags {
        PARSE_OPT_LASTARG_DEFAULT = 1 << 4,
        PARSE_OPT_NODASH = 1 << 5,
        PARSE_OPT_LITERAL_ARGHELP = 1 << 6,
+       PARSE_OPT_FROM_ALIAS = 1 << 7,
        PARSE_OPT_SHELL_EVAL = 1 << 8,
        PARSE_OPT_NOCOMPLETE = 1 << 9,
        PARSE_OPT_COMP_ARG = 1 << 10,