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Subject[patch 10/71] USB: handle zero-length usbfs submissions correctly
2.6.30-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Alan Stern <stern@rowland.harvard.edu>

commit 9180135bc80ab11199d482b6111e23f74d65af4a upstream.

This patch (as1262) fixes a bug in usbfs: It refuses to accept
zero-length transfers, and it insists that the buffer pointer be valid
even if there is no data being transferred.

The patch also consolidates a bunch of repetitive access_ok() checks
into a single check, which incidentally fixes the lack of such a check
for Isochronous URBs.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/core/devio.c | 41 ++++++++++++++++++++---------------------
1 file changed, 20 insertions(+), 21 deletions(-)

--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -982,7 +982,7 @@ static int proc_do_submiturb(struct dev_
USBDEVFS_URB_ZERO_PACKET |
USBDEVFS_URB_NO_INTERRUPT))
return -EINVAL;
- if (!uurb->buffer)
+ if (uurb->buffer_length > 0 && !uurb->buffer)
return -EINVAL;
if (!(uurb->type == USBDEVFS_URB_TYPE_CONTROL &&
(uurb->endpoint & ~USB_ENDPOINT_DIR_MASK) == 0)) {
@@ -1038,11 +1038,6 @@ static int proc_do_submiturb(struct dev_
is_in = 0;
uurb->endpoint &= ~USB_DIR_IN;
}
- if (!access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,
- uurb->buffer, uurb->buffer_length)) {
- kfree(dr);
- return -EFAULT;
- }
snoop(&ps->dev->dev, "control urb: bRequest=%02x "
"bRrequestType=%02x wValue=%04x "
"wIndex=%04x wLength=%04x\n",
@@ -1062,9 +1057,6 @@ static int proc_do_submiturb(struct dev_
uurb->number_of_packets = 0;
if (uurb->buffer_length > MAX_USBFS_BUFFER_SIZE)
return -EINVAL;
- if (!access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,
- uurb->buffer, uurb->buffer_length))
- return -EFAULT;
snoop(&ps->dev->dev, "bulk urb\n");
break;

@@ -1106,28 +1098,35 @@ static int proc_do_submiturb(struct dev_
return -EINVAL;
if (uurb->buffer_length > MAX_USBFS_BUFFER_SIZE)
return -EINVAL;
- if (!access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,
- uurb->buffer, uurb->buffer_length))
- return -EFAULT;
snoop(&ps->dev->dev, "interrupt urb\n");
break;

default:
return -EINVAL;
}
- as = alloc_async(uurb->number_of_packets);
- if (!as) {
+ if (uurb->buffer_length > 0 &&
+ !access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,
+ uurb->buffer, uurb->buffer_length)) {
kfree(isopkt);
kfree(dr);
- return -ENOMEM;
+ return -EFAULT;
}
- as->urb->transfer_buffer = kmalloc(uurb->buffer_length, GFP_KERNEL);
- if (!as->urb->transfer_buffer) {
+ as = alloc_async(uurb->number_of_packets);
+ if (!as) {
kfree(isopkt);
kfree(dr);
- free_async(as);
return -ENOMEM;
}
+ if (uurb->buffer_length > 0) {
+ as->urb->transfer_buffer = kmalloc(uurb->buffer_length,
+ GFP_KERNEL);
+ if (!as->urb->transfer_buffer) {
+ kfree(isopkt);
+ kfree(dr);
+ free_async(as);
+ return -ENOMEM;
+ }
+ }
as->urb->dev = ps->dev;
as->urb->pipe = (uurb->type << 30) |
__create_pipe(ps->dev, uurb->endpoint & 0xf) |
@@ -1169,7 +1168,7 @@ static int proc_do_submiturb(struct dev_
kfree(isopkt);
as->ps = ps;
as->userurb = arg;
- if (uurb->endpoint & USB_DIR_IN)
+ if (is_in && uurb->buffer_length > 0)
as->userbuffer = uurb->buffer;
else
as->userbuffer = NULL;
@@ -1179,9 +1178,9 @@ static int proc_do_submiturb(struct dev_
as->uid = cred->uid;
as->euid = cred->euid;
security_task_getsecid(current, &as->secid);
- if (!is_in) {
+ if (!is_in && uurb->buffer_length > 0) {
if (copy_from_user(as->urb->transfer_buffer, uurb->buffer,
- as->urb->transfer_buffer_length)) {
+ uurb->buffer_length)) {
free_async(as);
return -EFAULT;
}



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