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firmware: qemu_fw_cfg: fix kobject leak in probe error path

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commit 47a1db8e79 upstream.

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

Commit fe3c606843 ("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: 75f3e8e47f ("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>
This commit is contained in:
Johan Hovold 2021-12-01 14:25:26 +01:00 committed by Greg Kroah-Hartman
parent 1cc36ed561
commit 5c69ba9e80
1 changed files with 6 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
drivers/firmware/qemu_fw_cfg.c
View file

@ -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;
}