firmware: qemu_fw_cfg: fix sysfs information leak

Make sure to always NUL-terminate file names retrieved from the firmware
to avoid accessing data beyond the entry slab buffer and exposing it
through sysfs in case the firmware data is corrupt.

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/20211201132528.30025-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2021-12-01 14:25:27 +01:00 committed by Greg Kroah-Hartman
parent 47a1db8e79
commit 433b7cd1e7

View File

@ -598,7 +598,7 @@ static int fw_cfg_register_file(const struct fw_cfg_file *f)
/* set file entry information */
entry->size = be32_to_cpu(f->size);
entry->select = be16_to_cpu(f->select);
memcpy(entry->name, f->name, FW_CFG_MAX_FILE_PATH);
strscpy(entry->name, f->name, FW_CFG_MAX_FILE_PATH);
/* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */
err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,