diff: fix crash with --find-object outside repository

PATCH In review Michael Montalbo via GitGitGadget 2 participants 2 messages Feb 28 – Mar 2

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Michael Montalbo via GitGitGadget

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2026-02-28 20:31 UTC #0 lore raw

PATCH 1/1 diff: fix crash with --find-object outside repository

From: Michael Montalbo <[email protected]>

When "git diff --find-object=<oid>" is run outside a git repository, the option parsing callback eagerly resolves the OID via repo_get_oid(), which reaches get_main_ref_store() and hits a BUG() assertion because no repository has been set up.

Check startup_info->have_repository before attempting to resolve the OID, and return a user-friendly error instead.

Signed-off-by Michael Montalbo <[email protected]>

---
diff: fix crash with --find-object outside repository

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2057%2Fmmontalbo%2Ffix-find-object-crash-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2057/mmontalbo/fix-find-object-crash-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2057

 diff.c                   |  2 ++
 t/t4053-diff-no-index.sh | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff.c +2 -0

index a68ddd2168..8f0f141be7 100644
@@ -5215,6 +5215,8 @@ static int diff_opt_find_object(const struct option *option,
 	struct object_id oid;
 
 	BUG_ON_OPT_NEG(unset);
+	if (!startup_info->have_repository)
+		return error(_("--find-object requires a git repository"));
 	if (repo_get_oid(the_repository, arg, &oid))
 		return error(_("unable to resolve '%s'"), arg);

t/t4053-diff-no-index.sh +10 -0

index 69599279e9..15076dfe0d 100755
@@ -76,6 +76,16 @@ test_expect_success 'git diff --no-index executed outside repo gives correct err
 	)
 '
 
+test_expect_success 'git diff --find-object outside repo fails gracefully' '
+	(
+		GIT_CEILING_DIRECTORIES=$TRASH_DIRECTORY/non &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		test_must_fail git diff --find-object=abc123 2>err &&
+		test_grep "find-object requires a git repository" err
+	)
+'
+
 test_expect_success 'diff D F and diff F D' '
 	(
 		cd repo &&

base-commit: 67ad42147a7acc2af6074753ebd03d904476118f

Signature · 1 line

gitgitgadget

Junio C Hamano

2026-03-02 16:29 UTC #1 lore raw

Quoted 27 lines · Michael Montalbo via GitGitGadget

From: Michael Montalbo <[email protected]>
When "git diff --find-object=<oid>" is run outside a git repository, the option parsing callback eagerly resolves the OID via repo_get_oid(), which reaches get_main_ref_store() and hits a BUG() assertion because no repository has been set up.
Check startup_info->have_repository before attempting to resolve the OID, and return a user-friendly error instead.
Signed-off-by Michael Montalbo <[email protected]>
---
diff: fix crash with --find-object outside repository
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2057%2Fmmontalbo%2Ffix-find-object-crash-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2057/mmontalbo/fix-find-object-crash-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2057
 diff.c                   |  2 ++
 t/t4053-diff-no-index.sh | 10 ++++++++++
 2 files changed, 12 insertions(+)
diff.c +0 -0
index a68ddd2168..8f0f141be7 100644

diff.c static int diff_opt_find_object(const struct option *option, · line 5221

Quoted 7 lines

diff.c +2 -0

@@ -5215,6 +5215,8 @@ static int diff_opt_find_object(const struct option *option,
 	struct object_id oid;
 
 	BUG_ON_OPT_NEG(unset);
+	if (!startup_info->have_repository)
+		return error(_("--find-object requires a git repository"));
 	if (repo_get_oid(the_repository, arg, &oid))
 		return error(_("unable to resolve '%s'"), arg);

Makes sense.

Quoted 7 lines

t/t4053-diff-no-index.sh +0 -0

index 69599279e9..15076dfe0d 100755
@@ -76,6 +76,16 @@ test_expect_success 'git diff --no-index executed outside repo gives correct err
 	)
 '

t/t4053-diff-no-index.sh test_expect_success 'git diff --no-index executed outside repo gives correct err · line 87

Quoted 10 lines

t/t4053-diff-no-index.sh +9 -0

 
+test_expect_success 'git diff --find-object outside repo fails gracefully' '
+	(
+		GIT_CEILING_DIRECTORIES=$TRASH_DIRECTORY/non &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		test_must_fail git diff --find-object=abc123 2>err &&
+		test_grep "find-object requires a git repository" err
+	)
+'

Looks good, too.

Will queue. Thanks.

Quoted 5 lines

t/t4053-diff-no-index.sh +0 -0
 test_expect_success 'diff D F and diff F D' '
 	(
 		cd repo &&
base-commit: 67ad42147a7acc2af6074753ebd03d904476118f