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usb: gadget: f_mtp: Fix issue of NULL pointer access in mtp_read

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MTP usb device node created as a part of mtp function init call.
Userspace can read/write to MTP device using this node. If MTP is
not enabled in the composition and trying to read mtp_usb dev node
from the userspace leading to null pointer access in mtp_read.

Do not access ep OUT maxpacket size in mtp_read. First block on mtp_read
until the state become online which doesn't wakeup from the thread and
expecting for the read completion or state change which occurs as
a part of set_alt.

Change-Id: Icbee5fe7ae2c02b2bca185a0dc7587eb4940058a
Signed-off-by: ChandanaKishori Chiluveru <cchilu@codeaurora.org>
Signed-off-by: Azhar Shaikh <azhars@codeaurora.org>
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
This commit is contained in:
Hemant Kumar 2016-05-02 11:09:00 -07:00 • committed by Kyle Yan
parent ff1259b38e
commit 9f9acf870f
1 changed files with 5 additions and 4 deletions
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9
drivers/usb/gadget/function/f_mtp.c
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@ -586,10 +586,6 @@ static ssize_t mtp_read(struct file *fp, char __user *buf,
DBG(cdev, "mtp_read(%zu)\n", count);
len = ALIGN(count, dev->ep_out->maxpacket);
if (len > mtp_rx_req_len)
return -EINVAL;
/* we will block until we're online */
DBG(cdev, "mtp_read: waiting for online state\n");
ret = wait_event_interruptible(dev->read_wq,
@ -598,6 +594,11 @@ static ssize_t mtp_read(struct file *fp, char __user *buf,
r = ret;
goto done;
}
len = ALIGN(count, dev->ep_out->maxpacket);
if (len > mtp_rx_req_len)
return -EINVAL;
spin_lock_irq(&dev->lock);
if (dev->state == STATE_CANCELED) {
/* report cancelation to userspace */