From 6f957724b94cb19f5c1c97efd01dd4df8ced323c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 9 Jul 2015 11:20:01 -0700 Subject: [PATCH] Fix firmware loader uevent buffer NULL pointer dereference The firmware class uevent function accessed the "fw_priv->buf" buffer without the proper locking and testing for NULL. This is an old bug (looks like it goes back to 2012 and commit 1244691c73b2: "firmware loader: introduce firmware_buf"), but for some reason it's triggering only now in 4.2-rc1. Shuah Khan is trying to bisect what it is that causes this to trigger more easily, but in the meantime let's just fix the bug since others are hitting it too (at least Ingo reports having seen it as well). Reported-and-tested-by: Shuah Khan Acked-by: Ming Lei Cc: Greg Kroah-Hartman Signed-off-by: Linus Torvalds --- drivers/base/firmware_class.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index 9c4288362a8e..894bda114224 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -563,10 +563,8 @@ static void fw_dev_release(struct device *dev) kfree(fw_priv); } -static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env) +static int do_firmware_uevent(struct firmware_priv *fw_priv, struct kobj_uevent_env *env) { - struct firmware_priv *fw_priv = to_firmware_priv(dev); - if (add_uevent_var(env, "FIRMWARE=%s", fw_priv->buf->fw_id)) return -ENOMEM; if (add_uevent_var(env, "TIMEOUT=%i", loading_timeout)) @@ -577,6 +575,18 @@ static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env) return 0; } +static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env) +{ + struct firmware_priv *fw_priv = to_firmware_priv(dev); + int err = 0; + + mutex_lock(&fw_lock); + if (fw_priv->buf) + err = do_firmware_uevent(fw_priv, env); + mutex_unlock(&fw_lock); + return err; +} + static struct class firmware_class = { .name = "firmware", .class_attrs = firmware_class_attrs, -- 2.25.1