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USB: change the memory limits in usbfs URB submission

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For a long time people have complained about the limitations imposed
by usbfs.  URBs coming from userspace are not allowed to have transfer
buffers larger than a more-or-less arbitrary maximum.

While it is generally a good idea to avoid large transfer buffers
(because the data has to be bounced to/from a contiguous kernel-space
buffer), it's not the kernel's job to enforce such limits.  Programs
should be allowed to submit URBs as large as they like; if there isn't
sufficient contiguous memory available then the submission will fail
with a simple ENOMEM error.

On the other hand, we would like to prevent programs from submitting a
lot of small URBs and using up all the DMA-able kernel memory.  To
that end, this patch (as1497) replaces the old limits on individual
transfer buffers with a single global limit on the total amount of
memory in use by usbfs.  The global limit is set to 16 MB as a nice
compromise value: not too big, but large enough to hold about 300 ms
of data for high-speed transfers.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2011-11-17 16:41:25 -05:00 committed by Greg Kroah-Hartman
parent 52fb743d3a
commit add1aaeabe
1 changed files with 57 additions and 19 deletions
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76
drivers/usb/core/devio.c
View file

@ -86,6 +86,7 @@ struct async {
void __user *userbuffer;
void __user *userurb;
struct urb *urb;
unsigned int mem_usage;
int status;
u32 secid;
u8 bulk_addr;
@ -108,8 +109,26 @@ enum snoop_when {
#define USB_DEVICE_DEV MKDEV(USB_DEVICE_MAJOR, 0)
#define MAX_USBFS_BUFFER_SIZE 16384
/* Limit on the total amount of memory we can allocate for transfers */
#define MAX_USBFS_MEMORY_USAGE 16777216 /* 16 MB */
static atomic_t usbfs_memory_usage; /* Total memory currently allocated */
/* Check whether it's okay to allocate more memory for a transfer */
static int usbfs_increase_memory_usage(unsigned amount)
{
atomic_add(amount, &usbfs_memory_usage);
if (atomic_read(&usbfs_memory_usage) <= MAX_USBFS_MEMORY_USAGE)
return 0;
atomic_sub(amount, &usbfs_memory_usage);
return -ENOMEM;
}
/* Memory for a transfer is being deallocated */
static void usbfs_decrease_memory_usage(unsigned amount)
{
atomic_sub(amount, &usbfs_memory_usage);
}
static int connected(struct dev_state *ps)
{
@ -253,6 +272,7 @@ static void free_async(struct async *as)
kfree(as->urb->transfer_buffer);
kfree(as->urb->setup_packet);
usb_free_urb(as->urb);
usbfs_decrease_memory_usage(as->mem_usage);
kfree(as);
}
@ -792,9 +812,15 @@ static int proc_control(struct dev_state *ps, void __user *arg)
wLength = ctrl.wLength; /* To suppress 64k PAGE_SIZE warning */
if (wLength > PAGE_SIZE)
return -EINVAL;
ret = usbfs_increase_memory_usage(PAGE_SIZE + sizeof(struct urb) +
sizeof(struct usb_ctrlrequest));
if (ret)
return ret;
tbuf = (unsigned char *)__get_free_page(GFP_KERNEL);
if (!tbuf)
return -ENOMEM;
if (!tbuf) {
ret = -ENOMEM;
goto done;
}
tmo = ctrl.timeout;
snoop(&dev->dev, "control urb: bRequestType=%02x "
"bRequest=%02x wValue=%04x "
@ -852,6 +878,8 @@ static int proc_control(struct dev_state *ps, void __user *arg)
ret = i;
done:
free_page((unsigned long) tbuf);
usbfs_decrease_memory_usage(PAGE_SIZE + sizeof(struct urb) +
sizeof(struct usb_ctrlrequest));
return ret;
}
@ -879,10 +907,15 @@ static int proc_bulk(struct dev_state *ps, void __user *arg)
if (!usb_maxpacket(dev, pipe, !(bulk.ep & USB_DIR_IN)))
return -EINVAL;
len1 = bulk.len;
if (len1 > MAX_USBFS_BUFFER_SIZE)
if (len1 > MAX_USBFS_MEMORY_USAGE)
return -EINVAL;
if (!(tbuf = kmalloc(len1, GFP_KERNEL)))
return -ENOMEM;
ret = usbfs_increase_memory_usage(len1 + sizeof(struct urb));
if (ret)
return ret;
if (!(tbuf = kmalloc(len1, GFP_KERNEL))) {
ret = -ENOMEM;
goto done;
}
tmo = bulk.timeout;
if (bulk.ep & 0x80) {
if (len1 && !access_ok(VERIFY_WRITE, bulk.data, len1)) {
@ -919,6 +952,7 @@ static int proc_bulk(struct dev_state *ps, void __user *arg)
ret = (i < 0 ? i : len2);
done:
kfree(tbuf);
usbfs_decrease_memory_usage(len1 + sizeof(struct urb));
return ret;
}
@ -1097,14 +1131,14 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
}
if (!ep)
return -ENOENT;
u = 0;
switch(uurb->type) {
case USBDEVFS_URB_TYPE_CONTROL:
if (!usb_endpoint_xfer_control(&ep->desc))
return -EINVAL;
/* min 8 byte setup packet,
* max 8 byte setup plus an arbitrary data stage */
if (uurb->buffer_length < 8 ||
uurb->buffer_length > (8 + MAX_USBFS_BUFFER_SIZE))
/* min 8 byte setup packet */
if (uurb->buffer_length < 8)
return -EINVAL;
dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
if (!dr)
@ -1138,6 +1172,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
__le16_to_cpup(&dr->wValue),
__le16_to_cpup(&dr->wIndex),
__le16_to_cpup(&dr->wLength));
u = sizeof(struct usb_ctrlrequest);
break;
case USBDEVFS_URB_TYPE_BULK:
@ -1151,8 +1186,6 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
goto interrupt_urb;
}
uurb->number_of_packets = 0;
if (uurb->buffer_length > MAX_USBFS_BUFFER_SIZE)
return -EINVAL;
break;
case USBDEVFS_URB_TYPE_INTERRUPT:
@ -1160,8 +1193,6 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
return -EINVAL;
interrupt_urb:
uurb->number_of_packets = 0;
if (uurb->buffer_length > MAX_USBFS_BUFFER_SIZE)
return -EINVAL;
break;
case USBDEVFS_URB_TYPE_ISO:
@ -1188,17 +1219,18 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
}
totlen += isopkt[u].length;
}
/* 3072 * 64 microframes */
if (totlen > 196608) {
ret = -EINVAL;
goto error;
}
u *= sizeof(struct usb_iso_packet_descriptor);
uurb->buffer_length = totlen;
break;
default:
return -EINVAL;
}
if (uurb->buffer_length > MAX_USBFS_MEMORY_USAGE) {
ret = -EINVAL;
goto error;
}
if (uurb->buffer_length > 0 &&
!access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,
uurb->buffer, uurb->buffer_length)) {
@ -1210,6 +1242,12 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
ret = -ENOMEM;
goto error;
}
u += sizeof(struct async) + sizeof(struct urb) + uurb->buffer_length;
ret = usbfs_increase_memory_usage(u);
if (ret)
goto error;
as->mem_usage = u;
if (uurb->buffer_length > 0) {
as->urb->transfer_buffer = kmalloc(uurb->buffer_length,
GFP_KERNEL);