Commit 5c69ba9e authored Dec 01, 2021 by Johan Hovold Committed by Greg Kroah-Hartman Jan 20, 2022

firmware: qemu_fw_cfg: fix kobject leak in probe error path



commit 47a1db8e797da01a1309bf42e0c0d771d4e4d4f3 upstream.

An initialised kobject must be freed using kobject_put() to avoid
leaking associated resources (e.g. the object name).

Commit fe3c60684377 ("firmware: Fix a reference count leak.") "fixed"
the leak in the first error path of the file registration helper but
left the second one unchanged. This "fix" would however result in a NULL
pointer dereference due to the release function also removing the never
added entry from the fw_cfg_entry_cache list. This has now been
addressed.

Fix the remaining kobject leak by restoring the common error path and
adding the missing kobject_put().

Fixes: 75f3e8e4 ("firmware: introduce sysfs driver for QEMU's fw_cfg device")
Cc: stable@vger.kernel.org      # 4.6
Cc: Gabriel Somlo <somlo@cmu.edu>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20211201132528.30025-3-johan@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 1cc36ed5

drivers/firmware/qemu_fw_cfg.c

+6 −7

Original line number	Diff line number	Diff line
		@@ -600,15 +600,13 @@ static int fw_cfg_register_file(const struct fw_cfg_file *f)
		/* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */
		err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,
		fw_cfg_sel_ko, "%d", entry->select);
		if (err) {
		kobject_put(&entry->kobj);
		return err;
		}
		if (err)
		goto err_put_entry;

		/* add raw binary content access */
		err = sysfs_create_bin_file(&entry->kobj, &fw_cfg_sysfs_attr_raw);
		if (err)
		goto err_add_raw;
		goto err_del_entry;

		/* try adding "/sys/firmware/qemu_fw_cfg/by_name/" symlink */
		fw_cfg_build_symlink(fw_cfg_fname_kset, &entry->kobj, entry->name);
		@@ -617,9 +615,10 @@ static int fw_cfg_register_file(const struct fw_cfg_file *f)
		fw_cfg_sysfs_cache_enlist(entry);
		return 0;

		err_add_raw:
		err_del_entry:
		kobject_del(&entry->kobj);
		kfree(entry);
		err_put_entry:
		kobject_put(&entry->kobj);
		return err;
		}