[PATCH] usbip: Fix uninitialized symbol 'nents' in stub_recv_cmd_submit()
From: Suwan Kim <hidden>
Date: 2019-11-11 14:11:05
Also in:
lkml
Subsystem:
the rest, usb over ip driver, usb subsystem · Maintainers:
Linus Torvalds, Valentina Manea, Shuah Khan, Greg Kroah-Hartman
Smatch reported that nents is not initialized and used in
stub_recv_cmd_submit(). nents is currently initialized by sgl_alloc()
and used to allocate multiple URBs when host controller doesn't
support scatter-gather DMA. The use of uninitialized nents means that
buf_len is zero and use_sg is true. But buffer length should not be
zero when an URB uses scatter-gather DMA.
To prevent this situation, add the conditional that checks buf_len
and use_sg. And move the use of nents right after the sgl_alloc() to
avoid the use of uninitialized nents.
If the error occurs, it adds SDEV_EVENT_ERROR_MALLOC and stub_priv
will be released by stub event handler and connection will be shut
down.
Fixes: ea44d190764b ("usbip: Implement SG support to vhci-hcd and stub driver")
Reported-by: kbuild test robot <redacted>
Reported-by: Dan Carpenter <redacted>
Signed-off-by: Suwan Kim <redacted>
---
drivers/usb/usbip/stub_rx.c | 50 ++++++++++++++++++++++++-------------
1 file changed, 32 insertions(+), 18 deletions(-)
diff --git a/drivers/usb/usbip/stub_rx.c b/drivers/usb/usbip/stub_rx.c
index 66edfeea68fe..e2b019532234 100644
--- a/drivers/usb/usbip/stub_rx.c
+++ b/drivers/usb/usbip/stub_rx.c@@ -470,18 +470,50 @@ static void stub_recv_cmd_submit(struct stub_device *sdev, if (pipe == -1) return; + /* + * Smatch reported the error case where use_sg is true and buf_len is 0. + * In this case, It adds SDEV_EVENT_ERROR_MALLOC and stub_priv will be + * released by stub event handler and connection will be shut down. + */ priv = stub_priv_alloc(sdev, pdu); if (!priv) return; buf_len = (unsigned long long)pdu->u.cmd_submit.transfer_buffer_length; + if (use_sg && !buf_len) { + dev_err(&udev->dev, "sg buffer with zero length\n"); + goto err_malloc; + } + /* allocate urb transfer buffer, if needed */ if (buf_len) { if (use_sg) { sgl = sgl_alloc(buf_len, GFP_KERNEL, &nents); if (!sgl) goto err_malloc; + + /* Check if the server's HCD supports SG */ + if (!udev->bus->sg_tablesize) { + /* + * If the server's HCD doesn't support SG, break + * a single SG request into several URBs and map + * each SG list entry to corresponding URB + * buffer. The previously allocated SG list is + * stored in priv->sgl (If the server's HCD + * support SG, SG list is stored only in + * urb->sg) and it is used as an indicator that + * the server split single SG request into + * several URBs. Later, priv->sgl is used by + * stub_complete() and stub_send_ret_submit() to + * reassemble the divied URBs. + */ + support_sg = 0; + num_urbs = nents; + priv->completed_urbs = 0; + pdu->u.cmd_submit.transfer_flags &= + ~URB_DMA_MAP_SG; + } } else { buffer = kzalloc(buf_len, GFP_KERNEL); if (!buffer)
@@ -489,24 +521,6 @@ static void stub_recv_cmd_submit(struct stub_device *sdev, } } - /* Check if the server's HCD supports SG */ - if (use_sg && !udev->bus->sg_tablesize) { - /* - * If the server's HCD doesn't support SG, break a single SG - * request into several URBs and map each SG list entry to - * corresponding URB buffer. The previously allocated SG - * list is stored in priv->sgl (If the server's HCD support SG, - * SG list is stored only in urb->sg) and it is used as an - * indicator that the server split single SG request into - * several URBs. Later, priv->sgl is used by stub_complete() and - * stub_send_ret_submit() to reassemble the divied URBs. - */ - support_sg = 0; - num_urbs = nents; - priv->completed_urbs = 0; - pdu->u.cmd_submit.transfer_flags &= ~URB_DMA_MAP_SG; - } - /* allocate urb array */ priv->num_urbs = num_urbs; priv->urbs = kmalloc_array(num_urbs, sizeof(*priv->urbs), GFP_KERNEL);
--
2.21.0