From fd9a899ed63280ed80fe45a20be1def12332d529 Mon Sep 17 00:00:00 2001 From: Manoj Chourasia Date: Mon, 22 Jul 2013 15:33:13 +0530 Subject: [PATCH] HID: hidraw: correctly deallocate memory on device disconnect This changes puts the commit 4fe9f8e203f back in place with the fixes for slab corruption because of the commit. When a device is unplugged, wait for all processes that have opened the device to close before deallocating the device. This commit was solving kernel crash because of the corruption in rb tree of vmalloc. The rootcause was the device data pointer was geting excessed after the memory associated with hidraw was freed. The commit 4fe9f8e203f was buggy as it was also freeing the hidraw first and then calling delete operation on the list associated with that hidraw leading to slab corruption. Signed-off-by: Manoj Chourasia --- drivers/hid/hidraw.c | 60 +++++++++++++++++++++----------------------------- 1 file changed, 25 insertions(+), 35 deletions(-) diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c index a745163..612a655 100644 --- a/drivers/hid/hidraw.c +++ b/drivers/hid/hidraw.c @@ -113,7 +113,7 @@ static ssize_t hidraw_send_report(struct file *file, const char __user *buffer, __u8 *buf; int ret = 0; - if (!hidraw_table[minor]) { + if (!hidraw_table[minor] || !hidraw_table[minor]->exist) { ret = -ENODEV; goto out; } @@ -261,7 +261,7 @@ static int hidraw_open(struct inode *inode, struct file *file) } mutex_lock(&minors_lock); - if (!hidraw_table[minor]) { + if (!hidraw_table[minor] || !hidraw_table[minor]->exist) { err = -ENODEV; goto out_unlock; } @@ -302,39 +302,38 @@ static int hidraw_fasync(int fd, struct file *file, int on) return fasync_helper(fd, file, on, &list->fasync); } +static void drop_ref(struct hidraw *hidraw, int exists_bit) +{ + if (exists_bit) { + hid_hw_close(hidraw->hid); + hidraw->exist = 0; + if (hidraw->open) + wake_up_interruptible(&hidraw->wait); + } else { + --hidraw->open; + } + + if (!hidraw->open && !hidraw->exist) { + device_destroy(hidraw_class, MKDEV(hidraw_major, hidraw->minor)); + hidraw_table[hidraw->minor] = NULL; + kfree(hidraw); + } +} + static int hidraw_release(struct inode * inode, struct file * file) { unsigned int minor = iminor(inode); - struct hidraw *dev; struct hidraw_list *list = file->private_data; - int ret; - int i; mutex_lock(&minors_lock); - if (!hidraw_table[minor]) { - ret = -ENODEV; - goto unlock; - } list_del(&list->node); - dev = hidraw_table[minor]; - if (!--dev->open) { - if (list->hidraw->exist) { - hid_hw_power(dev->hid, PM_HINT_NORMAL); - hid_hw_close(dev->hid); - } else { - kfree(list->hidraw); - } - } - - for (i = 0; i < HIDRAW_BUFFER_SIZE; ++i) - kfree(list->buffer[i].value); kfree(list); - ret = 0; -unlock: - mutex_unlock(&minors_lock); - return ret; + drop_ref(hidraw_table[minor], 0); + + mutex_unlock(&minors_lock); + return 0; } static long hidraw_ioctl(struct file *file, unsigned int cmd, @@ -539,18 +538,9 @@ void hidraw_disconnect(struct hid_device *hid) struct hidraw *hidraw = hid->hidraw; mutex_lock(&minors_lock); - hidraw->exist = 0; - - device_destroy(hidraw_class, MKDEV(hidraw_major, hidraw->minor)); - hidraw_table[hidraw->minor] = NULL; + drop_ref(hidraw, 1); - if (hidraw->open) { - hid_hw_close(hid); - wake_up_interruptible(&hidraw->wait); - } else { - kfree(hidraw); - } mutex_unlock(&minors_lock); } EXPORT_SYMBOL_GPL(hidraw_disconnect); -- 1.7.9.5