From 55a3a4d27cb160b9fd61c145a8819c3d7f029ce2 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 commit 6f957724b94cb19f5c1c97efd01dd4df8ced323c upstream. 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 Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- 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 9cf8dc7448e..30d575a09ad 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -543,10 +543,8 @@ static void fw_dev_release(struct device *dev) module_put(THIS_MODULE); } -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)) @@ -557,6 +555,18 @@ 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, -- 2.20.1