unpack-trees: don't leak memory in verify_clean_subdirectory()

avar · gitster · commit e5a917fcf42d · 2021-10-07T15:29:02.000-07:00
Fix two different but related memory leaks in verify_clean_subdirectory(). We leaked both the "pathbuf" if read_directory() returned non-zero, and we never cleaned up our own "struct dir_struct" either. * "pathbuf": When the read_directory() call followed by the free(pathbuf) was added in c819353 (Fix switching to a branch with D/F when current branch has file D., 2007-03-15) we didn't bother to free() before we called die(). But when this code was later libified in 203a2fe (Allow callers of unpack_trees() to handle failure, 2008-02-07) we started to leak as we returned data to the caller. This fixes that memory leak, which can be observed under SANITIZE=leak with e.g. the "t1001-read-tree-m-2way.sh" test. * "struct dir_struct": We've leaked the dir_struct ever since this code was added back in c819353. When that commit was written there wasn't an equivalent of dir_clear(). Since it was added in 270be81 (dir.c: provide clear_directory() for reclaiming dir_struct memory, 2013-01-06) we've omitted freeing the memory allocated here. This memory leak could also be observed under SANITIZE=leak and the "t1001-read-tree-m-2way.sh" test. This makes all the test in "t1001-read-tree-m-2way.sh" pass under "GIT_TEST_PASSING_SANITIZE_LEAK=true", we'd previously die in tests 25, 26 & 28. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t1001-read-tree-m-2way.sh b/t/t1001-read-tree-m-2way.sh
@@ -20,6 +20,8 @@ In the test, these paths are used:
 	rezrov  - in H, deleted in M
 	yomin   - not in H or M
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-read-tree.sh
 
diff --git a/unpack-trees.c b/unpack-trees.c
@@ -2136,9 +2136,10 @@ static int verify_clean_subdirectory(const struct cache_entry *ce,
 	if (o->dir)
 		d.exclude_per_dir = o->dir->exclude_per_dir;
 	i = read_directory(&d, o->src_index, pathbuf, namelen+1, NULL);
+	dir_clear(&d);
+	free(pathbuf);
 	if (i)
 		return add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
-	free(pathbuf);
 	return cnt;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -20,6 +20,8 @@ In the test, these paths are used:`
`20`	`20`	`rezrov - in H, deleted in M`
`21`	`21`	`yomin - not in H or M`
`22`	`22`	`'`
	`23`	`+`
	`24`	`+TEST_PASSES_SANITIZE_LEAK=true`
`23`	`25`	`. ./test-lib.sh`
`24`	`26`	`. "$TEST_DIRECTORY"/lib-read-tree.sh`
`25`	`27`