2021-08-06 14:53:24

by Tuo Li

Subject: [PATCH v2] 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.

Reported-by: TOTE Robot <[email protected]>
Signed-off-by: Tuo Li <[email protected]>
---
v2:
* Assign the return value of kmalloc_array() to a local variable and then
check it instead of assigning 0 to tx->num_desc when memory allocation
fails.
Thank Mike Marciniszyn for helpful advice.
---
drivers/infiniband/hw/hfi1/sdma.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/sdma.c b/drivers/infiniband/hw/hfi1/sdma.c
index eb15c310d63d..6ca8d065f44e 100644
--- 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 +3076,12 @@ 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;
--
2.25.1

2021-08-06 16:14:25

by Jason Gunthorpe

Subject: Re: [PATCH v2] IB/hfi1: Fix possible null-pointer dereference in _extend_sdma_tx_descs()

On Fri, Aug 06, 2021 at 01:39:53AM -0700, Tuo Li wrote:
> 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.
>
> Reported-by: TOTE Robot <[email protected]>
> Signed-off-by: Tuo Li <[email protected]>
> ---
> v2:
> * Assign the return value of kmalloc_array() to a local variable and then
> check it instead of assigning 0 to tx->num_desc when memory allocation
> fails.
> Thank Mike Marciniszyn for helpful advice.
> ---
> drivers/infiniband/hw/hfi1/sdma.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)

Fixes line?

Jason