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Subject[PATCH 4.4 203/241] media: smsusb: better handle optional alignment
Date
From: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

commit a47686636d84eaec5c9c6e84bd5f96bed34d526d upstream.

Most Siano devices require an alignment for the response.

Changeset f3be52b0056a ("media: usb: siano: Fix general protection fault in smsusb")
changed the logic with gets such aligment, but it now produces a
sparce warning:

drivers/media/usb/siano/smsusb.c: In function 'smsusb_init_device':
drivers/media/usb/siano/smsusb.c:447:37: warning: 'in_maxp' may be used uninitialized in this function [-Wmaybe-uninitialized]
447 | dev->response_alignment = in_maxp - sizeof(struct sms_msg_hdr);
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

The sparse message itself is bogus, but a broken (or fake) USB
eeprom could produce a negative value for response_alignment.

So, change the code in order to check if the result is not
negative.

Fixes: 31e0456de5be ("media: usb: siano: Fix general protection fault in smsusb")
CC: <stable@vger.kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/media/usb/siano/smsusb.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/media/usb/siano/smsusb.c
+++ b/drivers/media/usb/siano/smsusb.c
@@ -391,7 +391,7 @@ static int smsusb_init_device(struct usb
struct smsusb_device_t *dev;
void *mdev;
int i, rc;
- int in_maxp = 0;
+ int align = 0;

/* create device object */
dev = kzalloc(sizeof(struct smsusb_device_t), GFP_KERNEL);
@@ -409,14 +409,14 @@ static int smsusb_init_device(struct usb

if (desc->bEndpointAddress & USB_DIR_IN) {
dev->in_ep = desc->bEndpointAddress;
- in_maxp = usb_endpoint_maxp(desc);
+ align = usb_endpoint_maxp(desc) - sizeof(struct sms_msg_hdr);
} else {
dev->out_ep = desc->bEndpointAddress;
}
}

pr_debug("in_ep = %02x, out_ep = %02x\n", dev->in_ep, dev->out_ep);
- if (!dev->in_ep || !dev->out_ep) { /* Missing endpoints? */
+ if (!dev->in_ep || !dev->out_ep || align < 0) { /* Missing endpoints? */
smsusb_term_device(intf);
return -ENODEV;
}
@@ -435,7 +435,7 @@ static int smsusb_init_device(struct usb
/* fall-thru */
default:
dev->buffer_size = USB2_BUFFER_SIZE;
- dev->response_alignment = in_maxp - sizeof(struct sms_msg_hdr);
+ dev->response_alignment = align;

params.flags |= SMS_DEVICE_FAMILY2;
break;

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