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[PATCH v3 3/7] builtin/gc: fix leaking config values

From
Patrick Steinhardt <ps@pks.im>
Date
Aug 16, 2024, 10:45 UTC
Message-ID
<310e361371efc156c3aaac94439bdbeaa965155f.1723804990.git.ps@pks.im>
In-Reply-To
<cover.1723804990.git.ps@pks.im>

We're leaking config values in git-gc(1) when those values are tracked as strings. Introduce a new `gc_config_release()` function that releases this memory to plug those leaks and release old values before populating the config fields via `git_config_string()` et al.

Note that there is one small gotcha here with the "--prune" option. Next to passing a string, this option also accepts the "--no-prune" option that overrides the default or configured value. We thus need to discern between the option not having been passed by the user and the negative variant of it. This is done by using a simple sentinel value that lets us discern these cases.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 builtin/gc.c     | 108 +++++++++++++++++++++++++++++++++++------------
 t/t5304-prune.sh |   1 +
 2 files changed, 82 insertions(+), 27 deletions(-)
diff --git a/builtin/gc.c b/builtin/gc.c
index eee7401647..a93cfa147e 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -139,9 +139,9 @@ struct gc_config {
 	int gc_auto_threshold;
 	int gc_auto_pack_limit;
 	int detach_auto;
-	const char *gc_log_expire;
-	const char *prune_expire;
-	const char *prune_worktrees_expire;
+	char *gc_log_expire;
+	char *prune_expire;
+	char *prune_worktrees_expire;
 	char *repack_filter;
 	char *repack_filter_to;
 	unsigned long big_pack_threshold;
@@ -157,15 +157,25 @@ struct gc_config {
 	.gc_auto_threshold = 6700, \
 	.gc_auto_pack_limit = 50, \
 	.detach_auto = 1, \
-	.gc_log_expire = "1.day.ago", \
-	.prune_expire = "2.weeks.ago", \
-	.prune_worktrees_expire = "3.months.ago", \
+	.gc_log_expire = xstrdup("1.day.ago"), \
+	.prune_expire = xstrdup("2.weeks.ago"), \
+	.prune_worktrees_expire = xstrdup("3.months.ago"), \
 	.max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE, \
 }
 
+static void gc_config_release(struct gc_config *cfg)
+{
+	free(cfg->gc_log_expire);
+	free(cfg->prune_expire);
+	free(cfg->prune_worktrees_expire);
+	free(cfg->repack_filter);
+	free(cfg->repack_filter_to);
+}
+
 static void gc_config(struct gc_config *cfg)
 {
 	const char *value;
+	char *owned = NULL;
 
 	if (!git_config_get_value("gc.packrefs", &value)) {
 		if (value && !strcmp(value, "notbare"))
@@ -185,15 +195,34 @@ static void gc_config(struct gc_config *cfg)
 	git_config_get_bool("gc.autodetach", &cfg->detach_auto);
 	git_config_get_bool("gc.cruftpacks", &cfg->cruft_packs);
 	git_config_get_ulong("gc.maxcruftsize", &cfg->max_cruft_size);
-	git_config_get_expiry("gc.pruneexpire", (char **) &cfg->prune_expire);
-	git_config_get_expiry("gc.worktreepruneexpire", (char **) &cfg->prune_worktrees_expire);
-	git_config_get_expiry("gc.logexpiry", (char **) &cfg->gc_log_expire);
+
+	if (!git_config_get_expiry("gc.pruneexpire", &owned)) {
+		free(cfg->prune_expire);
+		cfg->prune_expire = owned;
+	}
+
+	if (!git_config_get_expiry("gc.worktreepruneexpire", &owned)) {
+		free(cfg->prune_worktrees_expire);
+		cfg->prune_worktrees_expire = owned;
+	}
+
+	if (!git_config_get_expiry("gc.logexpiry", &owned)) {
+		free(cfg->gc_log_expire);
+		cfg->gc_log_expire = owned;
+	}
 
 	git_config_get_ulong("gc.bigpackthreshold", &cfg->big_pack_threshold);
 	git_config_get_ulong("pack.deltacachesize", &cfg->max_delta_cache_size);
 
-	git_config_get_string("gc.repackfilter", &cfg->repack_filter);
-	git_config_get_string("gc.repackfilterto", &cfg->repack_filter_to);
+	if (!git_config_get_string("gc.repackfilter", &owned)) {
+		free(cfg->repack_filter);
+		cfg->repack_filter = owned;
+	}
+
+	if (!git_config_get_string("gc.repackfilterto", &owned)) {
+		free(cfg->repack_filter_to);
+		cfg->repack_filter_to = owned;
+	}
 
 	git_config(git_default_config, NULL);
 }
@@ -644,12 +673,15 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	struct child_process rerere_cmd = CHILD_PROCESS_INIT;
 	struct maintenance_run_opts opts = {0};
 	struct gc_config cfg = GC_CONFIG_INIT;
+	const char *prune_expire_sentinel = "sentinel";
+	const char *prune_expire_arg = prune_expire_sentinel;
+	int ret;
 
 	struct option builtin_gc_options[] = {
 		OPT__QUIET(&quiet, N_("suppress progress reporting")),
-		{ OPTION_STRING, 0, "prune", &cfg.prune_expire, N_("date"),
+		{ OPTION_STRING, 0, "prune", &prune_expire_arg, N_("date"),
 			N_("prune unreferenced objects"),
-			PARSE_OPT_OPTARG, NULL, (intptr_t)cfg.prune_expire },
+			PARSE_OPT_OPTARG, NULL, (intptr_t)prune_expire_arg },
 		OPT_BOOL(0, "cruft", &cfg.cruft_packs, N_("pack unreferenced objects separately")),
 		OPT_MAGNITUDE(0, "max-cruft-size", &cfg.max_cruft_size,
 			      N_("with --cruft, limit the size of new cruft packs")),
@@ -673,8 +705,8 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	strvec_pushl(&prune_worktrees, "worktree", "prune", "--expire", NULL);
 	strvec_pushl(&rerere, "rerere", "gc", NULL);
 
-	/* default expiry time, overwritten in gc_config */
 	gc_config(&cfg);
+
 	if (parse_expiry_date(cfg.gc_log_expire, &gc_log_expire_time))
 		die(_("failed to parse gc.logExpiry value %s"), cfg.gc_log_expire);
 
@@ -686,6 +718,10 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	if (argc > 0)
 		usage_with_options(builtin_gc_usage, builtin_gc_options);
 
+	if (prune_expire_arg != prune_expire_sentinel) {
+		free(cfg.prune_expire);
+		cfg.prune_expire = xstrdup_or_null(prune_expire_arg);
+	}
 	if (cfg.prune_expire && parse_expiry_date(cfg.prune_expire, &dummy))
 		die(_("failed to parse prune expiry value %s"), cfg.prune_expire);
 
@@ -703,8 +739,11 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 		/*
 		 * Auto-gc should be least intrusive as possible.
 		 */
-		if (!need_to_gc(&cfg))
-			return 0;
+		if (!need_to_gc(&cfg)) {
+			ret = 0;
+			goto out;
+		}
+
 		if (!quiet) {
 			if (cfg.detach_auto)
 				fprintf(stderr, _("Auto packing the repository in background for optimum performance.\n"));
@@ -713,17 +752,22 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 			fprintf(stderr, _("See \"git help gc\" for manual housekeeping.\n"));
 		}
 		if (cfg.detach_auto) {
-			int ret = report_last_gc_error();
-
-			if (ret == 1)
+			ret = report_last_gc_error();
+			if (ret == 1) {
 				/* Last gc --auto failed. Skip this one. */
-				return 0;
-			else if (ret)
+				ret = 0;
+				goto out;
+
+			} else if (ret) {
 				/* an I/O error occurred, already reported */
-				return ret;
+				goto out;
+			}
+
+			if (lock_repo_for_gc(force, &pid)) {
+				ret = 0;
+				goto out;
+			}
 
-			if (lock_repo_for_gc(force, &pid))
-				return 0;
 			gc_before_repack(&opts, &cfg); /* dies on failure */
 			delete_tempfile(&pidfile);
 
@@ -749,8 +793,11 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 
 	name = lock_repo_for_gc(force, &pid);
 	if (name) {
-		if (opts.auto_flag)
-			return 0; /* be quiet on --auto */
+		if (opts.auto_flag) {
+			ret = 0;
+			goto out; /* be quiet on --auto */
+		}
+
 		die(_("gc is already running on machine '%s' pid %"PRIuMAX" (use --force if not)"),
 		    name, (uintmax_t)pid);
 	}
@@ -826,6 +873,8 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	if (!daemonized)
 		unlink(git_path("gc.log"));
 
+out:
+	gc_config_release(&cfg);
 	return 0;
 }
 
@@ -1511,6 +1560,8 @@ static int maintenance_run(int argc, const char **argv, const char *prefix)
 			PARSE_OPT_NONEG, task_option_parse),
 		OPT_END()
 	};
+	int ret;
+
 	memset(&opts, 0, sizeof(opts));
 
 	opts.quiet = !isatty(2);
@@ -1532,7 +1583,10 @@ static int maintenance_run(int argc, const char **argv, const char *prefix)
 	if (argc != 0)
 		usage_with_options(builtin_maintenance_run_usage,
 				   builtin_maintenance_run_options);
-	return maintenance_run_tasks(&opts, &cfg);
+
+	ret = maintenance_run_tasks(&opts, &cfg);
+	gc_config_release(&cfg);
+	return ret;
 }
 
 static char *get_maintpath(void)
diff --git a/t/t5304-prune.sh b/t/t5304-prune.sh
index 1f1f664871..e641df0116 100755
--- a/t/t5304-prune.sh
+++ b/t/t5304-prune.sh
@@ -7,6 +7,7 @@ test_description='prune'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 day=$((60*60*24))
-- 
2.46.0.46.g406f326d27.dirty
Previous: Patrick SteinhardtNext: Patrick Steinhardt
Message 45 of 79 in “builtin/maintenance: fix auto-detach with non-standard tasks”
  1. 0/7 builtin/maintenance: fix auto-detach with non-standard tasksPatrick Steinhardt, Aug 13, 2024
  2. 1/7 config: fix constness of out parameter for `git_config_get_expiry()`Patrick Steinhardt, Aug 13, 2024
  3. 2/7 builtin/gc: refactor to read config into structurePatrick Steinhardt, Aug 13, 2024
  4. James LiuAug 15, 2024
  5. Patrick SteinhardtAug 15, 2024
  6. Derrick StoleeAug 15, 2024
  7. 3/7 builtin/gc: fix leaking config valuesPatrick Steinhardt, Aug 13, 2024
  8. James LiuAug 15, 2024
  9. Patrick SteinhardtAug 15, 2024
  10. Derrick StoleeAug 15, 2024
  11. 4/7 builtin/gc: stop processing log file on signalPatrick Steinhardt, Aug 13, 2024
  12. James LiuAug 15, 2024
  13. 5/7 builtin/gc: add a `--detach` flagPatrick Steinhardt, Aug 13, 2024
  14. 6/7 builtin/maintenance: add a `--detach` flagPatrick Steinhardt, Aug 13, 2024
  15. 7/7 builtin/maintenance: fix auto-detach with non-standard tasksPatrick Steinhardt, Aug 13, 2024
  16. Phillip WoodAug 13, 2024
  17. Patrick SteinhardtAug 13, 2024
  18. Phillip WoodAug 13, 2024
  19. Patrick SteinhardtAug 14, 2024
  20. Phillip WoodAug 14, 2024
  21. Patrick SteinhardtAug 15, 2024
  22. James LiuAug 15, 2024
  23. Patrick SteinhardtAug 15, 2024
  24. Derrick StoleeAug 15, 2024
  25. James LiuAug 15, 2024
  26. 0/7 builtin/maintenance: fix auto-detach with non-standard tasksPatrick Steinhardt, Aug 15, 2024
  27. 2/7 builtin/gc: refactor to read config into structurePatrick Steinhardt, Aug 15, 2024
  28. 1/7 config: fix constness of out parameter for `git_config_get_expiry()`Patrick Steinhardt, Aug 15, 2024
  29. 6/7 builtin/maintenance: add a `--detach` flagPatrick Steinhardt, Aug 15, 2024
  30. 5/7 builtin/gc: add a `--detach` flagPatrick Steinhardt, Aug 15, 2024
  31. Junio C HamanoAug 15, 2024
  32. Junio C HamanoAug 15, 2024
  33. Patrick SteinhardtAug 16, 2024
  34. 4/7 builtin/gc: stop processing log file on signalPatrick Steinhardt, Aug 15, 2024
  35. 7/7 run-command: fix detaching when running auto maintenancePatrick Steinhardt, Aug 15, 2024
  36. Junio C HamanoAug 15, 2024
  37. Patrick SteinhardtAug 16, 2024
  38. 3/7 builtin/gc: fix leaking config valuesPatrick Steinhardt, Aug 15, 2024
  39. Derrick StoleeAug 15, 2024
  40. Junio C HamanoAug 15, 2024
  41. Patrick SteinhardtAug 16, 2024
  42. 0/7 builtin/maintenance: fix auto-detach with non-standard tasksPatrick Steinhardt, Aug 16, 2024
  43. 1/7 config: fix constness of out parameter for `git_config_get_expiry()`Patrick Steinhardt, Aug 16, 2024
  44. 2/7 builtin/gc: refactor to read config into structurePatrick Steinhardt, Aug 16, 2024
  45. 3/7 builtin/gc: fix leaking config valuesPatrick Steinhardt, Aug 16, 2024
  46. 4/7 builtin/gc: stop processing log file on signalPatrick Steinhardt, Aug 16, 2024
  47. 5/7 builtin/gc: add a `--detach` flagPatrick Steinhardt, Aug 16, 2024
  48. 6/7 builtin/maintenance: add a `--detach` flagPatrick Steinhardt, Aug 16, 2024
  49. Jeff KingAug 17, 2024
  50. Jeff KingAug 17, 2024
  51. Patrick SteinhardtAug 19, 2024
  52. 7/7 run-command: fix detaching when running auto maintenancePatrick Steinhardt, Aug 16, 2024
  53. Jeff KingAug 17, 2024
  54. Patrick SteinhardtAug 19, 2024
  55. 0/3 Fixups for git-maintenance(1) testsPatrick Steinhardt, Aug 19, 2024
  56. 1/3 t7900: fix flaky test due to leaking background jobPatrick Steinhardt, Aug 19, 2024
  57. Jeff KingAug 19, 2024
  58. Patrick SteinhardtAug 19, 2024
  59. Jeff KingAug 19, 2024
  60. Patrick SteinhardtAug 19, 2024
  61. 2/3 t7900: exercise detaching via trace2 regionsPatrick Steinhardt, Aug 19, 2024
  62. Jeff KingAug 19, 2024
  63. Patrick SteinhardtAug 19, 2024
  64. Junio C HamanoAug 21, 2024
  65. Patrick SteinhardtAug 22, 2024
  66. Junio C HamanoAug 22, 2024
  67. 3/3 builtin/maintenance: fix loose objects task emitting pack hashPatrick Steinhardt, Aug 19, 2024
  68. Jeff KingAug 19, 2024
  69. Patrick SteinhardtAug 19, 2024
  70. Jeff KingAug 19, 2024
  71. Patrick SteinhardtAug 19, 2024
  72. Jeff KingAug 19, 2024
  73. Patrick SteinhardtAug 20, 2024
  74. Junio C HamanoAug 20, 2024
  75. Junio C HamanoAug 19, 2024
  76. Jeff KingAug 19, 2024
  77. Patrick SteinhardtAug 19, 2024
  78. Patrick SteinhardtAug 19, 2024
  79. Patrick SteinhardtAug 19, 2024

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