Re: [PATCH v3] IB/hfi1: Fix possible null-pointer dereference in _extend_sdma_tx_descs()

On Fri, Aug 06, 2021 at 06:30:29AM -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.

Fixes: 7724105686e7 ("IB/hfi1: add driver files")
Reported-by: TOTE Robot <redacted>
Signed-off-by: Tuo Li <redacted>
Tested-by: Mike Marciniszyn <redacted>
Acked-by: Mike Marciniszyn <redacted>
---
v3:
* Add fixes line.
  Thank Jason Gunthorpe for helpful advice.
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(-)

I fixed the wonky code formatting and applied to for-rc, thanks

Jason