@matheusbsbs / matheus-bagliano / commits / 68cce04a02

merge: fix leak with merge.defaultToUpstream

By default the setting 'merge.defaultToUpstream' for git-merge(1) is set to 'true', which means when `git merge` is invoked with no arguments it merges the upstream branch configured for the current branch. With this configuration set to 'true', setup_with_upstream() is called. That function allocates an array of arguments and hands it back to cmd_merge() via its `argv` parameter. This array is never freed, so cmd_merge() leaks it on every invocation. Track the allocated array in a separate variable and free it at the end. The leak has been present since 93e535a5b7 (merge: merge with the default upstream branch without argument, 2011-03-24). Although the leak sanitizer was enabled for tests in fc1ddf42af (t: remove TEST_PASSES_SANITIZE_LEAK annotations, 2024-11-21), it went unnoticed because no test calls `git merge` without arguments, exercising the default-to-upstream path. Add such a test in t7600, which fails under the leak sanitizer without this fix. Signed-off-by: Toon Claes <toon@iotcl.com> Acked-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Toon Claes committed Jul 28, 2026 at 15:00 UTC 68cce04a028cac13fa1fd7a368801fac3d8b156b

2 files changed +22 -2

builtin/merge.c

+5 -2

@@ -1372,7 +1372,7 @@ int cmd_merge(int argc,

1372 struct commit_list *common = NULL;

1373 const char *best_strategy = NULL, *wt_strategy = NULL;

1374 struct commit_list *remoteheads = NULL, *p;

1375 - void *branch_to_free;

1375 + void *branch_to_free, *argv_to_free = NULL;

1376 int orig_argc = argc;

1377 int merge_log_config = -1;

1378

@@ -1516,8 +1516,10 @@ int cmd_merge(int argc,

1516 option_commit = 1;

1517

1518 if (!argc) {

1519 - if (default_to_upstream)

1519 + if (default_to_upstream) {

1520 argc = setup_with_upstream(&argv);

1521 + argv_to_free = argv;

1522 + }

1523 else

1524 die(_("No commit specified and merge.defaultToUpstream not set."));

1525 } else if (argc == 1 && !strcmp(argv[0], "-")) {

@@ -1885,6 +1887,7 @@ done:

1887 }

1888 strbuf_release(&buf);

1889 free(branch_to_free);

1890 + free(argv_to_free);

1891 free(pull_twohead);

1892 free(pull_octopus);

1893 discard_index(the_repository->index);

t/t7600-merge.sh

+17

@@ -1165,4 +1165,21 @@ test_expect_success 'suggested names are not ambiguous' '

1165 grep remotes/origin/not-local stderr

1166 '

1167

1168 +test_expect_success 'merge with no argument defaults to upstream' '

1169 + test_when_finished "rm -rf upstream downstream" &&

1170 + git init upstream &&

1171 + (

1172 + cd upstream &&

1173 + test_commit one &&

1174 + test_commit two

1175 + ) &&

1176 + git clone upstream downstream &&

1177 + (

1178 + cd downstream &&

1179 + git reset --hard HEAD^ &&

1180 + git merge &&

1181 + test_cmp_rev origin/main HEAD

1182 + )

1183 +'

1184 +

1185 test_done