The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 1b656e9aad7f4886ed466094d1dc5ee4dd900d20 Mon Sep 17 00:00:00 2001 From: Johan Hovold johan@kernel.org Date: Wed, 1 Dec 2021 14:25:27 +0100 Subject: [PATCH] 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: 75f3e8e47f38 ("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: Michael S. Tsirkin mst@redhat.com
diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c index ccb7ed62452f..f08e056ed0ae 100644 --- a/drivers/firmware/qemu_fw_cfg.c +++ b/drivers/firmware/qemu_fw_cfg.c @@ -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,