@matheusbsbs / matheus-bagliano / commits / 98e4015593

builtin/difftool: intialize some hashmap variables

When running a dir-diff command that produces no diff, variables `wt_modified` and `tmp_modified` are used while uninitialized, causing: $ /home/smarchi/src/git/git-difftool --dir-diff master free(): invalid pointer [1] 334004 IOT instruction (core dumped) /home/smarchi/src/git/git-difftool --dir-diff master $ valgrind --track-origins=yes /home/smarchi/src/git/git-difftool --dir-diff master ... Invalid free() / delete / delete[] / realloc() at 0x48478EF: free (vg_replace_malloc.c:989) by 0x422CAC: hashmap_clear_ (hashmap.c:208) by 0x283830: run_dir_diff (difftool.c:667) by 0x284103: cmd_difftool (difftool.c:801) by 0x238E0F: run_builtin (git.c:484) by 0x2392B9: handle_builtin (git.c:750) by 0x2399BC: cmd_main (git.c:921) by 0x356FEF: main (common-main.c:64) Address 0x1ffefff180 is on thread 1's stack in frame #2, created by run_dir_diff (difftool.c:358) ... If taking any `goto finish` path before these variables are initialized, `hashmap_clear_and_free()` operates on uninitialized data, sometimes causing a crash. This regression was introduced in 7f795a1715 (builtin/difftool: plug several trivial memory leaks, 2024-09-26). Fix it by initializing those variables with the `HASHMAP_INIT` macro. Add a test comparing the main branch to itself, resulting in no diff. Signed-off-by: Simon Marchi <simon.marchi@efficios.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Simon Marchi committed Nov 12, 2024 at 11:22 UTC 98e40155936e32a1d827f510f4d8c37f0eb3aef1

2 files changed +6 -4

builtin/difftool.c

+2 -4

@@ -376,7 +376,8 @@ static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,

376 struct checkout lstate, rstate;

377 int err = 0;

378 struct child_process cmd = CHILD_PROCESS_INIT;

379 - struct hashmap wt_modified, tmp_modified;

379 + struct hashmap wt_modified = HASHMAP_INIT(path_entry_cmp, NULL);

380 + struct hashmap tmp_modified = HASHMAP_INIT(path_entry_cmp, NULL);

381 int indices_loaded = 0;

382

383 workdir = repo_get_work_tree(the_repository);

@@ -601,9 +602,6 @@ static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,

602 * in the common case of --symlinks and the difftool updating

603 * files through the symlink.

604 */

604 - hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);

605 - hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);

606 -

605 for (i = 0; i < wtindex.cache_nr; i++) {

606 struct hashmap_entry dummy;

607 const char *name = wtindex.cache[i]->name;

t/t7800-difftool.sh

@@ -666,6 +666,10 @@ run_dir_diff_test 'difftool --dir-diff syncs worktree without unstaged change' '

666 test_cmp expect file

667 '

668

669 +run_dir_diff_test 'difftool --dir-diff with no diff' '

670 + git difftool -d main main

671 +'

672 +

673 write_script modify-file <<\EOF

674 echo "new content" >file

675 EOF