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[PATCH 25/29] merge: fix leaking merge bases

From
Patrick Steinhardt <ps@pks.im>
Date
Jun 3, 2024, 09:48 UTC
Message-ID
<5441f1e2ef3f33840588e623386c685b890ab052.1717402439.git.ps@pks.im>
In-Reply-To
<cover.1717402439.git.ps@pks.im>

When calling either the recursive or the ORT merge machineries we need to provide a list of merge bases. The ownership of that parameter is then implicitly transferred to the callee, which is somewhat fishy. Furthermore, that list may leak in some cases where the merge machinery runs into an error, thus causing a memory leak.

Refactor the code such that we stop transferring ownership. Instead, the merge machinery will now create its own local copies of the passed in list as required if they need to modify the list. Free the list at the callsites as required.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 builtin/merge-tree.c       |  1 +
 builtin/merge.c            |  2 ++
 commit.c                   |  2 +-
 commit.h                   |  2 +-
 log-tree.c                 |  1 +
 merge-ort-wrappers.c       |  2 +-
 merge-ort-wrappers.h       |  2 +-
 merge-ort.c                | 12 ++++++----
 merge-ort.h                |  2 +-
 merge-recursive.c          | 49 +++++++++++++++++++++++---------------
 merge-recursive.h          |  2 +-
 sequencer.c                |  1 +
 t/t3430-rebase-merges.sh   |  1 +
 t/t6402-merge-rename.sh    |  1 +
 t/t6430-merge-recursive.sh |  1 +
 t/t6436-merge-overwrite.sh |  1 +
 t/t7611-merge-abort.sh     |  1 +
 17 files changed, 54 insertions(+), 29 deletions(-)
diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index 1082d919fd..dab2fdc2a6 100644
--- a/builtin/merge-tree.c
+++ b/builtin/merge-tree.c
@@ -482,6 +482,7 @@ static int real_merge(struct merge_tree_options *o,
 			die(_("refusing to merge unrelated histories"));
 		merge_bases = reverse_commit_list(merge_bases);
 		merge_incore_recursive(&opt, merge_bases, parent1, parent2, &result);
+		free_commit_list(merge_bases);
 	}
 
 	if (result.clean < 0)
diff --git a/builtin/merge.c b/builtin/merge.c
index 682c6ed868..1120a6e2f8 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -746,6 +746,8 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 		else
 			clean = merge_recursive(&o, head, remoteheads->item,
 						reversed, &result);
+		free_commit_list(reversed);
+
 		if (clean < 0) {
 			rollback_lock_file(&lock);
 			return 2;
diff --git a/commit.c b/commit.c
index f674eca320..1386b12df1 100644
--- a/commit.c
+++ b/commit.c
@@ -680,7 +680,7 @@ unsigned commit_list_count(const struct commit_list *l)
 	return c;
 }
 
-struct commit_list *copy_commit_list(struct commit_list *list)
+struct commit_list *copy_commit_list(const struct commit_list *list)
 {
 	struct commit_list *head = NULL;
 	struct commit_list **pp = &head;
diff --git a/commit.h b/commit.h
index 442e50ff24..acabb05785 100644
--- a/commit.h
+++ b/commit.h
@@ -181,7 +181,7 @@ struct commit_list *commit_list_insert_by_date(struct commit *item,
 void commit_list_sort_by_date(struct commit_list **list);
 
 /* Shallow copy of the input list */
-struct commit_list *copy_commit_list(struct commit_list *list);
+struct commit_list *copy_commit_list(const struct commit_list *list);
 
 /* Modify list in-place to reverse it, returning new head; list will be tail */
 struct commit_list *reverse_commit_list(struct commit_list *list);
diff --git a/log-tree.c b/log-tree.c
index 41416de4e3..91b96d83a0 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -1047,6 +1047,7 @@ static int do_remerge_diff(struct rev_info *opt,
 	log_tree_diff_flush(opt);
 
 	/* Cleanup */
+	free_commit_list(bases);
 	cleanup_additional_headers(&opt->diffopt);
 	strbuf_release(&parent1_desc);
 	strbuf_release(&parent2_desc);
diff --git a/merge-ort-wrappers.c b/merge-ort-wrappers.c
index 4acedf3c33..d6f6135996 100644
--- a/merge-ort-wrappers.c
+++ b/merge-ort-wrappers.c
@@ -48,7 +48,7 @@ int merge_ort_nonrecursive(struct merge_options *opt,
 int merge_ort_recursive(struct merge_options *opt,
 			struct commit *side1,
 			struct commit *side2,
-			struct commit_list *merge_bases,
+			const struct commit_list *merge_bases,
 			struct commit **result)
 {
 	struct tree *head = repo_get_commit_tree(opt->repo, side1);
diff --git a/merge-ort-wrappers.h b/merge-ort-wrappers.h
index 0c4c57adbb..90af1f69c5 100644
--- a/merge-ort-wrappers.h
+++ b/merge-ort-wrappers.h
@@ -19,7 +19,7 @@ int merge_ort_nonrecursive(struct merge_options *opt,
 int merge_ort_recursive(struct merge_options *opt,
 			struct commit *h1,
 			struct commit *h2,
-			struct commit_list *ancestors,
+			const struct commit_list *ancestors,
 			struct commit **result);
 
 #endif
diff --git a/merge-ort.c b/merge-ort.c
index eaede6cead..8ed8a4c9dc 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -5071,11 +5071,12 @@ static void merge_ort_nonrecursive_internal(struct merge_options *opt,
  * Originally from merge_recursive_internal(); somewhat adapted, though.
  */
 static void merge_ort_internal(struct merge_options *opt,
-			       struct commit_list *merge_bases,
+			       const struct commit_list *_merge_bases,
 			       struct commit *h1,
 			       struct commit *h2,
 			       struct merge_result *result)
 {
+	struct commit_list *merge_bases = copy_commit_list(_merge_bases);
 	struct commit *next;
 	struct commit *merged_merge_bases;
 	const char *ancestor_name;
@@ -5085,7 +5086,7 @@ static void merge_ort_internal(struct merge_options *opt,
 		if (repo_get_merge_bases(the_repository, h1, h2,
 					 &merge_bases) < 0) {
 			result->clean = -1;
-			return;
+			goto out;
 		}
 		/* See merge-ort.h:merge_incore_recursive() declaration NOTE */
 		merge_bases = reverse_commit_list(merge_bases);
@@ -5129,7 +5130,7 @@ static void merge_ort_internal(struct merge_options *opt,
 		opt->branch2 = "Temporary merge branch 2";
 		merge_ort_internal(opt, NULL, prev, next, result);
 		if (result->clean < 0)
-			return;
+			goto out;
 		opt->branch1 = saved_b1;
 		opt->branch2 = saved_b2;
 		opt->priv->call_depth--;
@@ -5152,6 +5153,9 @@ static void merge_ort_internal(struct merge_options *opt,
 					result);
 	strbuf_release(&merge_base_abbrev);
 	opt->ancestor = NULL;  /* avoid accidental re-use of opt->ancestor */
+
+out:
+	free_commit_list(merge_bases);
 }
 
 void merge_incore_nonrecursive(struct merge_options *opt,
@@ -5181,7 +5185,7 @@ void merge_incore_nonrecursive(struct merge_options *opt,
 }
 
 void merge_incore_recursive(struct merge_options *opt,
-			    struct commit_list *merge_bases,
+			    const struct commit_list *merge_bases,
 			    struct commit *side1,
 			    struct commit *side2,
 			    struct merge_result *result)
diff --git a/merge-ort.h b/merge-ort.h
index ce56ec1a78..6af97c0828 100644
--- a/merge-ort.h
+++ b/merge-ort.h
@@ -59,7 +59,7 @@ struct merge_result {
  *           first", 2006-08-09)
  */
 void merge_incore_recursive(struct merge_options *opt,
-			    struct commit_list *merge_bases,
+			    const struct commit_list *merge_bases,
 			    struct commit *side1,
 			    struct commit *side2,
 			    struct merge_result *result);
diff --git a/merge-recursive.c b/merge-recursive.c
index 832c8ef3f3..1ac0316cce 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -3633,15 +3633,16 @@ static int merge_trees_internal(struct merge_options *opt,
 static int merge_recursive_internal(struct merge_options *opt,
 				    struct commit *h1,
 				    struct commit *h2,
-				    struct commit_list *merge_bases,
+				    const struct commit_list *_merge_bases,
 				    struct commit **result)
 {
+	struct commit_list *merge_bases = copy_commit_list(_merge_bases);
 	struct commit_list *iter;
 	struct commit *merged_merge_bases;
 	struct tree *result_tree;
-	int clean;
 	const char *ancestor_name;
 	struct strbuf merge_base_abbrev = STRBUF_INIT;
+	int ret;
 
 	if (show(opt, 4)) {
 		output(opt, 4, _("Merging:"));
@@ -3651,8 +3652,10 @@ static int merge_recursive_internal(struct merge_options *opt,
 
 	if (!merge_bases) {
 		if (repo_get_merge_bases(the_repository, h1, h2,
-					 &merge_bases) < 0)
-			return -1;
+					 &merge_bases) < 0) {
+			ret = -1;
+			goto out;
+		}
 		merge_bases = reverse_commit_list(merge_bases);
 	}
 
@@ -3702,14 +3705,18 @@ static int merge_recursive_internal(struct merge_options *opt,
 		opt->branch1 = "Temporary merge branch 1";
 		opt->branch2 = "Temporary merge branch 2";
 		if (merge_recursive_internal(opt, merged_merge_bases, iter->item,
-					     NULL, &merged_merge_bases) < 0)
-			return -1;
+					     NULL, &merged_merge_bases) < 0) {
+			ret = -1;
+			goto out;
+		}
 		opt->branch1 = saved_b1;
 		opt->branch2 = saved_b2;
 		opt->priv->call_depth--;
 
-		if (!merged_merge_bases)
-			return err(opt, _("merge returned no commit"));
+		if (!merged_merge_bases) {
+			ret = err(opt, _("merge returned no commit"));
+			goto out;
+		}
 	}
 
 	/*
@@ -3726,17 +3733,16 @@ static int merge_recursive_internal(struct merge_options *opt,
 		repo_read_index(opt->repo);
 
 	opt->ancestor = ancestor_name;
-	clean = merge_trees_internal(opt,
-				     repo_get_commit_tree(opt->repo, h1),
-				     repo_get_commit_tree(opt->repo, h2),
-				     repo_get_commit_tree(opt->repo,
-							  merged_merge_bases),
-				     &result_tree);
-	strbuf_release(&merge_base_abbrev);
+	ret = merge_trees_internal(opt,
+				   repo_get_commit_tree(opt->repo, h1),
+				   repo_get_commit_tree(opt->repo, h2),
+				   repo_get_commit_tree(opt->repo,
+							merged_merge_bases),
+				   &result_tree);
 	opt->ancestor = NULL;  /* avoid accidental re-use of opt->ancestor */
-	if (clean < 0) {
+	if (ret < 0) {
 		flush_output(opt);
-		return clean;
+		goto out;
 	}
 
 	if (opt->priv->call_depth) {
@@ -3745,7 +3751,11 @@ static int merge_recursive_internal(struct merge_options *opt,
 		commit_list_insert(h1, &(*result)->parents);
 		commit_list_insert(h2, &(*result)->parents->next);
 	}
-	return clean;
+
+out:
+	strbuf_release(&merge_base_abbrev);
+	free_commit_list(merge_bases);
+	return ret;
 }
 
 static int merge_start(struct merge_options *opt, struct tree *head)
@@ -3827,7 +3837,7 @@ int merge_trees(struct merge_options *opt,
 int merge_recursive(struct merge_options *opt,
 		    struct commit *h1,
 		    struct commit *h2,
-		    struct commit_list *merge_bases,
+		    const struct commit_list *merge_bases,
 		    struct commit **result)
 {
 	int clean;
@@ -3895,6 +3905,7 @@ int merge_recursive_generic(struct merge_options *opt,
 	repo_hold_locked_index(opt->repo, &lock, LOCK_DIE_ON_ERROR);
 	clean = merge_recursive(opt, head_commit, next_commit, ca,
 				result);
+	free_commit_list(ca);
 	if (clean < 0) {
 		rollback_lock_file(&lock);
 		return clean;
diff --git a/merge-recursive.h b/merge-recursive.h
index 839eb6436e..3136c7cc2d 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -104,7 +104,7 @@ int merge_trees(struct merge_options *opt,
 int merge_recursive(struct merge_options *opt,
 		    struct commit *h1,
 		    struct commit *h2,
-		    struct commit_list *merge_bases,
+		    const struct commit_list *merge_bases,
 		    struct commit **result);
 
 /*
diff --git a/sequencer.c b/sequencer.c
index 1a54f18b43..9e90084692 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4315,6 +4315,7 @@ static int do_merge(struct repository *r,
 	strbuf_release(&ref_name);
 	rollback_lock_file(&lock);
 	free_commit_list(to_merge);
+	free_commit_list(bases);
 	return ret;
 }
 
diff --git a/t/t3430-rebase-merges.sh b/t/t3430-rebase-merges.sh
index 59b5d6b6f2..36ca126bcd 100755
--- a/t/t3430-rebase-merges.sh
+++ b/t/t3430-rebase-merges.sh
@@ -21,6 +21,7 @@ Initial setup:
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-rebase.sh
 . "$TEST_DIRECTORY"/lib-log-graph.sh
diff --git a/t/t6402-merge-rename.sh b/t/t6402-merge-rename.sh
index 2738b50c2a..729aac9842 100755
--- a/t/t6402-merge-rename.sh
+++ b/t/t6402-merge-rename.sh
@@ -4,6 +4,7 @@ test_description='Merge-recursive merging renames'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 modify () {
diff --git a/t/t6430-merge-recursive.sh b/t/t6430-merge-recursive.sh
index ca15e6dd6d..555f00f78a 100755
--- a/t/t6430-merge-recursive.sh
+++ b/t/t6430-merge-recursive.sh
@@ -5,6 +5,7 @@ test_description='merge-recursive backend test'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-merge.sh
 
diff --git a/t/t6436-merge-overwrite.sh b/t/t6436-merge-overwrite.sh
index 4f4376421e..ccc620477d 100755
--- a/t/t6436-merge-overwrite.sh
+++ b/t/t6436-merge-overwrite.sh
@@ -7,6 +7,7 @@ Do not overwrite changes.'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '
diff --git a/t/t7611-merge-abort.sh b/t/t7611-merge-abort.sh
index d6975ca48d..992a8f9874 100755
--- a/t/t7611-merge-abort.sh
+++ b/t/t7611-merge-abort.sh
@@ -25,6 +25,7 @@ Next, test git merge --abort with the following variables:
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '

-- 
2.45.1.410.g58bac47f8e.dirty
Previous: Patrick SteinhardtNext: Patrick Steinhardt
Message 36 of 74 in “Memory leak fixes (pt.2)”
  1. 00/29 Memory leak fixes (pt.2)Patrick Steinhardt, Jun 3, 2024
  2. 01/29 revision: fix memory leak when reversing revisionsPatrick Steinhardt, Jun 3, 2024
  3. 02/29 parse-options: fix leaks for users of OPT_FILENAMEPatrick Steinhardt, Jun 3, 2024
  4. Karthik NayakJun 6, 2024
  5. 03/29 notes-utils: free note trees when releasing copied notesPatrick Steinhardt, Jun 3, 2024
  6. Karthik NayakJun 6, 2024
  7. 04/29 bundle: plug leaks in `create_bundle()`Patrick Steinhardt, Jun 3, 2024
  8. 05/29 biultin/rev-parse: fix memory leaks in `--parseopt` modePatrick Steinhardt, Jun 3, 2024
  9. 06/29 merge-recursive: fix leaging rename conflict infoPatrick Steinhardt, Jun 3, 2024
  10. Karthik NayakJun 6, 2024
  11. 07/29 revision: fix leaking display notesPatrick Steinhardt, Jun 3, 2024
  12. 08/29 notes: fix memory leak when pruning notesPatrick Steinhardt, Jun 3, 2024
  13. 09/29 builtin/rev-list: fix leaking bitmap index when calculating disk usagePatrick Steinhardt, Jun 3, 2024
  14. 10/29 object-name: free leaking object contextsPatrick Steinhardt, Jun 3, 2024
  15. 11/29 builtin/difftool: plug memory leaks in `run_dir_diff()`Patrick Steinhardt, Jun 3, 2024
  16. 12/29 builtin/merge-recursive: fix leaking object ID basesPatrick Steinhardt, Jun 3, 2024
  17. 13/29 merge-recursive: fix memory leak when finalizing mergePatrick Steinhardt, Jun 3, 2024
  18. Karthik NayakJun 6, 2024
  19. Phillip WoodJun 6, 2024
  20. Karthik NayakJun 12, 2024
  21. 14/29 builtin/log: fix leaking commit list in git-cherry(1)Patrick Steinhardt, Jun 3, 2024
  22. 15/29 revision: free diff optionsPatrick Steinhardt, Jun 3, 2024
  23. 16/29 builtin/stash: fix leak in `show_stash()`Patrick Steinhardt, Jun 3, 2024
  24. 17/29 rerere: fix various trivial leaksPatrick Steinhardt, Jun 3, 2024
  25. 18/29 config: fix leaking "core.notesref" variablePatrick Steinhardt, Jun 3, 2024
  26. 19/29 commit: fix leaking parents when calling `commit_tree_extended()`Patrick Steinhardt, Jun 3, 2024
  27. 20/29 sequencer: fix leaking string buffer in `commit_staged_changes()`Patrick Steinhardt, Jun 3, 2024
  28. Phillip WoodJun 3, 2024
  29. Patrick SteinhardtJun 4, 2024
  30. Patrick SteinhardtJun 4, 2024
  31. Phillip WoodJun 4, 2024
  32. 21/29 apply: fix leaking string in `match_fragment()`Patrick Steinhardt, Jun 3, 2024
  33. 22/29 builtin/clone: plug leaking HEAD ref in `wanted_peer_refs()`Patrick Steinhardt, Jun 3, 2024
  34. 23/29 sequencer: fix memory leaks in `make_script_with_merges()`Patrick Steinhardt, Jun 3, 2024
  35. 24/29 builtin/merge: fix leaking `struct cmdnames` in `get_strategy()`Patrick Steinhardt, Jun 3, 2024
  36. 25/29 merge: fix leaking merge basesPatrick Steinhardt, Jun 3, 2024
  37. 26/29 line-range: plug leaking find functionsPatrick Steinhardt, Jun 3, 2024
  38. 27/29 blame: fix leaking data for blame scoreboardsPatrick Steinhardt, Jun 3, 2024
  39. 28/29 builtin/blame: fix leaking prefixed pathsPatrick Steinhardt, Jun 3, 2024
  40. 29/29 builtin/blame: fix leaking ignore revs filesPatrick Steinhardt, Jun 3, 2024
  41. Karthik NayakJun 6, 2024
  42. Patrick SteinhardtJun 7, 2024
  43. 00/29 Memory leak fixes (pt.2)Patrick Steinhardt, Jun 11, 2024
  44. 01/29 revision: fix memory leak when reversing revisionsPatrick Steinhardt, Jun 11, 2024
  45. 02/29 parse-options: fix leaks for users of OPT_FILENAMEPatrick Steinhardt, Jun 11, 2024
  46. 03/29 notes-utils: free note trees when releasing copied notesPatrick Steinhardt, Jun 11, 2024
  47. 04/29 bundle: plug leaks in `create_bundle()`Patrick Steinhardt, Jun 11, 2024
  48. 05/29 biultin/rev-parse: fix memory leaks in `--parseopt` modePatrick Steinhardt, Jun 11, 2024
  49. 06/29 merge-recursive: fix leaking rename conflict infoPatrick Steinhardt, Jun 11, 2024
  50. 07/29 revision: fix leaking display notesPatrick Steinhardt, Jun 11, 2024
  51. 08/29 notes: fix memory leak when pruning notesPatrick Steinhardt, Jun 11, 2024
  52. 09/29 builtin/rev-list: fix leaking bitmap index when calculating disk usagePatrick Steinhardt, Jun 11, 2024
  53. 10/29 object-name: free leaking object contextsPatrick Steinhardt, Jun 11, 2024
  54. 11/29 builtin/difftool: plug memory leaks in `run_dir_diff()`Patrick Steinhardt, Jun 11, 2024
  55. 12/29 builtin/merge-recursive: fix leaking object ID basesPatrick Steinhardt, Jun 11, 2024
  56. 13/29 merge-recursive: fix memory leak when finalizing mergePatrick Steinhardt, Jun 11, 2024
  57. 14/29 builtin/log: fix leaking commit list in git-cherry(1)Patrick Steinhardt, Jun 11, 2024
  58. 15/29 revision: free diff optionsPatrick Steinhardt, Jun 11, 2024
  59. 16/29 builtin/stash: fix leak in `show_stash()`Patrick Steinhardt, Jun 11, 2024
  60. 17/29 rerere: fix various trivial leaksPatrick Steinhardt, Jun 11, 2024
  61. 18/29 config: fix leaking "core.notesref" variablePatrick Steinhardt, Jun 11, 2024
  62. 19/29 commit: fix leaking parents when calling `commit_tree_extended()`Patrick Steinhardt, Jun 11, 2024
  63. 20/29 sequencer: fix leaking string buffer in `commit_staged_changes()`Patrick Steinhardt, Jun 11, 2024
  64. 21/29 apply: fix leaking string in `match_fragment()`Patrick Steinhardt, Jun 11, 2024
  65. 22/29 builtin/clone: plug leaking HEAD ref in `wanted_peer_refs()`Patrick Steinhardt, Jun 11, 2024
  66. 23/29 sequencer: fix memory leaks in `make_script_with_merges()`Patrick Steinhardt, Jun 11, 2024
  67. 24/29 builtin/merge: fix leaking `struct cmdnames` in `get_strategy()`Patrick Steinhardt, Jun 11, 2024
  68. 25/29 merge: fix leaking merge basesPatrick Steinhardt, Jun 11, 2024
  69. 26/29 line-range: plug leaking find functionsPatrick Steinhardt, Jun 11, 2024
  70. 27/29 blame: fix leaking data for blame scoreboardsPatrick Steinhardt, Jun 11, 2024
  71. 28/29 builtin/blame: fix leaking prefixed pathsPatrick Steinhardt, Jun 11, 2024
  72. 29/29 builtin/blame: fix leaking ignore revs filesPatrick Steinhardt, Jun 11, 2024
  73. Phillip WoodJun 12, 2024
  74. Karthik NayakJun 12, 2024

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