Re: [PATCH] USB: whci-hcd: add more checks for dma mapping error

From: Alexey Khoroshilov
Date: Fri Mar 25 2016 - 18:57:09 EST

On 26.03.2016 01:03, Vladimir Zapolskiy wrote:
On 25.03.2016 22:23, Alexey Khoroshilov wrote:
Fixing checks for dma mapping error in qset_fill_page_list(),
I have missed two similar problems in qset_add_urb_sg() and
in qset_add_urb_sg_linearize().

Found by Linux Driver Verification project (

Signed-off-by: Alexey Khoroshilov <khoroshilov@xxxxxxxxx>
drivers/usb/host/whci/qset.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/whci/qset.c b/drivers/usb/host/whci/qset.c
index 1a8e960d073b..a8e9b618e643 100644
--- a/drivers/usb/host/whci/qset.c
+++ b/drivers/usb/host/whci/qset.c
@@ -535,9 +535,11 @@ static int qset_add_urb_sg(struct whc *whc, struct whc_qset *qset, struct urb *u
list_for_each_entry(std, &qset->stds, list_node) {
if (std->ntds_remaining == -1) {
pl_len = std->num_pointers * sizeof(struct whc_page_list_entry);
- std->ntds_remaining = ntds--;
std->dma_addr = dma_map_single(whc->, std->pl_virt,
pl_len, DMA_TO_DEVICE);
+ if (dma_mapping_error(whc->, std->dma_addr))
+ return -EFAULT;

Resources are leaked on error path:
* std->pl_virt -- most probably, at least it is freed on error path above,
* dma mappings done in a loop before met error,

As far as I can see, it is not the case.
If qset_add_urb_sg() returns error code, the caller (qset_add_urb()) invokes qset_free_stds() that performs all resource deallocations.

As for the error path above, I consider it as a typical krealloc() pattern, since it does not frees memory allocated at previous iterations of the cycle.

Thank you,