IB/hfi1: Fix possible null-pointer dereference in _extend_sdma_tx_descs()

kmalloc_array() is called to allocate memory for tx->descp. If it fails,
the function __sdma_txclean() is called:
  __sdma_txclean(dd, tx);

However, in the function __sdma_txclean(), tx-descp is dereferenced if
tx->num_desc is not zero:
  sdma_unmap_desc(dd, &tx->descp[0]);

To fix this possible null-pointer dereference, assign the return value of
kmalloc_array() to a local variable descp, and then assign it to tx->descp
if it is not NULL. Otherwise, go to enomem.

Fixes: 7724105686e7 ("IB/hfi1: add driver files")
Link: https://lore.kernel.org/r/20210806133029.194964-1-islituo@gmail.com
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
Tested-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
Acked-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/hw/hfi1/sdma.c b/drivers/infiniband/hw/hfi1/sdma.c
index eb15c31..e83dc56 100644 (file)
--- a/drivers/infiniband/hw/hfi1/sdma.c
+++ b/drivers/infiniband/hw/hfi1/sdma.c
@@ -3055,6 +3055,7 @@ static void __sdma_process_event(struct sdma_engine *sde,
 static int _extend_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
 {
        int i;
+       struct sdma_desc *descp;
 
        /* Handle last descriptor */
        if (unlikely((tx->num_desc == (MAX_DESC - 1)))) {
@@ -3075,12 +3076,10 @@ static int _extend_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
        if (unlikely(tx->num_desc == MAX_DESC))
                goto enomem;
 
-       tx->descp = kmalloc_array(
-                       MAX_DESC,
-                       sizeof(struct sdma_desc),
-                       GFP_ATOMIC);
-       if (!tx->descp)
+       descp = kmalloc_array(MAX_DESC, sizeof(struct sdma_desc), GFP_ATOMIC);
+       if (!descp)
                goto enomem;
+       tx->descp = descp;
 
        /* reserve last descriptor for coalescing */
        tx->desc_limit = MAX_DESC - 1;