initramfs_test: kunit test for cpio.filesize > PATH_MAX

initramfs unpack skips over cpio entries where namesize > PATH_MAX,
instead of returning an error. Add coverage for this behaviour.

Signed-off-by: David Disseldorp <ddiss@suse.de>
Link: https://patch.msgid.link/20260114135051.4943-2-ddiss@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/init/initramfs_test.c b/init/initramfs_test.c
index 5d2db455e60c55941ad6b70c745bdae0b544f5d0..beb6e3cf78081b849ca108d74cd9a5c0cbac5c0b 100644 (file)
--- a/init/initramfs_test.c
+++ b/init/initramfs_test.c
@@ -447,6 +447,53 @@ out:
        kfree(tbufs);
 }
 
+static void __init initramfs_test_fname_path_max(struct kunit *test)
+{
+       char *err;
+       size_t len;
+       struct kstat st0, st1;
+       char fdata[] = "this file data will not be unpacked";
+       struct test_fname_path_max {
+               char fname_oversize[PATH_MAX + 1];
+               char fname_ok[PATH_MAX];
+               char cpio_src[(CPIO_HDRLEN + PATH_MAX + 3 + sizeof(fdata)) * 2];
+       } *tbufs = kzalloc(sizeof(struct test_fname_path_max), GFP_KERNEL);
+       struct initramfs_test_cpio c[] = { {
+               .magic = "070701",
+               .ino = 1,
+               .mode = S_IFDIR | 0777,
+               .nlink = 1,
+               .namesize = sizeof(tbufs->fname_oversize),
+               .fname = tbufs->fname_oversize,
+               .filesize = sizeof(fdata),
+               .data = fdata,
+       }, {
+               .magic = "070701",
+               .ino = 2,
+               .mode = S_IFDIR | 0777,
+               .nlink = 1,
+               .namesize = sizeof(tbufs->fname_ok),
+               .fname = tbufs->fname_ok,
+       } };
+
+       memset(tbufs->fname_oversize, '/', sizeof(tbufs->fname_oversize) - 1);
+       memset(tbufs->fname_ok, '/', sizeof(tbufs->fname_ok) - 1);
+       memcpy(tbufs->fname_oversize, "fname_oversize",
+              sizeof("fname_oversize") - 1);
+       memcpy(tbufs->fname_ok, "fname_ok", sizeof("fname_ok") - 1);
+       len = fill_cpio(c, ARRAY_SIZE(c), tbufs->cpio_src);
+
+       /* unpack skips over fname_oversize instead of returning an error */
+       err = unpack_to_rootfs(tbufs->cpio_src, len);
+       KUNIT_EXPECT_NULL(test, err);
+
+       KUNIT_EXPECT_EQ(test, init_stat("fname_oversize", &st0, 0), -ENOENT);
+       KUNIT_EXPECT_EQ(test, init_stat("fname_ok", &st1, 0), 0);
+       KUNIT_EXPECT_EQ(test, init_rmdir("fname_ok"), 0);
+
+       kfree(tbufs);
+}
+
 /*
  * The kunit_case/_suite struct cannot be marked as __initdata as this will be
  * used in debugfs to retrieve results after test has run.
@@ -459,6 +506,7 @@ static struct kunit_case __refdata initramfs_test_cases[] = {
        KUNIT_CASE(initramfs_test_hardlink),
        KUNIT_CASE(initramfs_test_many),
        KUNIT_CASE(initramfs_test_fname_pad),
+       KUNIT_CASE(initramfs_test_fname_path_max),
        {},
 };