Re: [PATCH 1/1] HID: hidraw: Add spinlock in struct hidraw to protect list
flat view
From: Yonghua Zheng <hidden>
Date: 2013-08-26 15:38:47
Subsystem:
hid core layer, the rest · Maintainers:
Jiri Kosina, Benjamin Tissoires, Linus Torvalds
Hi Jiri, Fix the conflict and update the patch:
From 7c06e1f3a5959e73a5b827bda67e7c1eaed7da67 Mon Sep 17 00:00:00 2001
From: Yonghua Zheng <redacted> Date: Wed, 14 Aug 2013 17:43:36 +0800 Subject: [PATCH 1/1] HID: hidraw: Add spinlock in struct hidraw to protect member list It is unsafe to call list_for_each_entry in hidraw_report_event to traverse each hidraw_list node without a lock protection, the list could be modified if someone calls hidraw_release and list_del to remove itself from the list, this can cause hidraw_report_event to touch a deleted list struct and panic. To prevent this, introduce a spinlock in struct hidraw to protect list from concurrent access. Signed-off-by: Yonghua Zheng <redacted>
diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index dbfe300..8918dd1 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c@@ -253,6 +253,7 @@ static int hidraw_open(struct inode *inode, struct file *file) unsigned int minor = iminor(inode); struct hidraw *dev; struct hidraw_list *list; + unsigned long flags; int err = 0; if (!(list = kzalloc(sizeof(struct hidraw_list), GFP_KERNEL))) {
@@ -266,11 +267,6 @@ static int hidraw_open(struct inode *inode, struct file *file) goto out_unlock; } - list->hidraw = hidraw_table[minor]; - mutex_init(&list->read_mutex); - list_add_tail(&list->node, &hidraw_table[minor]->list); - file->private_data = list; - dev = hidraw_table[minor]; if (!dev->open++) { err = hid_hw_power(dev->hid, PM_HINT_FULLON);
@@ -283,9 +279,16 @@ static int hidraw_open(struct inode *inode, struct file *file) if (err < 0) { hid_hw_power(dev->hid, PM_HINT_NORMAL); dev->open--; + goto out_unlock; } } + list->hidraw = hidraw_table[minor]; + mutex_init(&list->read_mutex); + spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags); + list_add_tail(&list->node, &hidraw_table[minor]->list); + spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags); + file->private_data = list; out_unlock: mutex_unlock(&minors_lock); out:
@@ -324,10 +327,13 @@ static int hidraw_release(struct inode * inode, struct file * file) { unsigned int minor = iminor(inode); struct hidraw_list *list = file->private_data; + unsigned long flags; mutex_lock(&minors_lock); + spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags); list_del(&list->node); + spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags); kfree(list); drop_ref(hidraw_table[minor], 0);
@@ -456,7 +462,9 @@ int hidraw_report_event(struct hid_device *hid, u8 *data, int len) struct hidraw *dev = hid->hidraw; struct hidraw_list *list; int ret = 0; + unsigned long flags; + spin_lock_irqsave(&dev->list_lock, flags); list_for_each_entry(list, &dev->list, node) { int new_head = (list->head + 1) & (HIDRAW_BUFFER_SIZE - 1);
@@ -471,6 +479,7 @@ int hidraw_report_event(struct hid_device *hid, u8 *data, int len) list->head = new_head; kill_fasync(&list->fasync, SIGIO, POLL_IN); } + spin_unlock_irqrestore(&dev->list_lock, flags); wake_up_interruptible(&dev->wait); return ret;
@@ -518,6 +527,7 @@ int hidraw_connect(struct hid_device *hid) } init_waitqueue_head(&dev->wait); + spin_lock_init(&dev->list_lock); INIT_LIST_HEAD(&dev->list); dev->hid = hid;
diff --git a/include/linux/hidraw.h b/include/linux/hidraw.h
index 2451662..ddf5261 100644
--- a/include/linux/hidraw.h
+++ b/include/linux/hidraw.h@@ -23,6 +23,7 @@ struct hidraw { wait_queue_head_t wait; struct hid_device *hid; struct device *dev; + spinlock_t list_lock; struct list_head list; };
--
1.7.9.5
Thanks
Yonghua
On Mon, Aug 26, 2013 at 02:03:18PM +0200, Jiri Kosina wrote:
> On Thu, 15 Aug 2013, Yonghua Zheng wrote:
>
> > As hidraw_report_event can be called from interrupt context, it is a mistake
> > to use mutex_lock for protecting the list member in my previous patch, so
> > update the patch which adds a spinlock in struct hidraw to protect the list
> > member from concurrent access:
>
> Hi,
>
> thanks for the patch.
>
> I already have
>
> commit 212a871a3934beccf43431608c27ed2e05a476ec
> Author: Manoj Chourasia <mchourasia@nvidia.com>
> Date: Mon Jul 22 15:33:13 2013 +0530
>
> HID: hidraw: correctly deallocate memory on device disconnect
>
> in the tree, which collides with your patch. Could you please check what
> changes are needed on top of it so that it makes sense for my 'for-next'
> branch, rebase, and resend to me?
>
> Thanks,
>
> --
> Jiri Kosina
> SUSE Labs
On Mon, Aug 26, 2013 at 02:03:18PM +0200, Jiri Kosina wrote:
> On Thu, 15 Aug 2013, Yonghua Zheng wrote:
>
> > As hidraw_report_event can be called from interrupt context, it is a mistake
> > to use mutex_lock for protecting the list member in my previous patch, so
> > update the patch which adds a spinlock in struct hidraw to protect the list
> > member from concurrent access:
>
> Hi,
>
> thanks for the patch.
>
> I already have
>
> commit 212a871a3934beccf43431608c27ed2e05a476ec
> Author: Manoj Chourasia <mchourasia@nvidia.com>
> Date: Mon Jul 22 15:33:13 2013 +0530
>
> HID: hidraw: correctly deallocate memory on device disconnect
>
> in the tree, which collides with your patch. Could you please check what
> changes are needed on top of it so that it makes sense for my 'for-next'
> branch, rebase, and resend to me?
>
> Thanks,
>
> --
> Jiri Kosina
> SUSE Labs