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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>
maint
Andrzej Hunt 2021-03-21 16:58:36 +00:00 committed by Junio C Hamano
parent 0171dbcb42
commit 64cc539fd2
2 changed files with 19 additions and 1 deletions
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19
parse-options.c
View File

@ -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);
}

1
parse-options.h
View File

@ -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,