[PATCH 5.4 11/76] RDMA/ocrdma: Fix use after free in ocrdma_dealloc_ucontext_pd()

[Greg Kroah-Hartman]

From: Tom Rix <trix@xxxxxxxxxx>

commit f2bc3af6353cb2a33dfa9d270d999d839eef54cb upstream.

In ocrdma_dealloc_ucontext_pd() uctx->cntxt_pd is assigned to the variable
pd and then after uctx->cntxt_pd is freed, the variable pd is passed to
function _ocrdma_dealloc_pd() which dereferences pd directly or through
its call to ocrdma_mbx_dealloc_pd().

Reorder the free using the variable pd.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 21a428a019c9 ("RDMA: Handle PD allocations by IB/core")
Link: https://lore.kernel.org/r/20201230024653.1516495-1-trix@xxxxxxxxxx
Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/infiniband/hw/ocrdma/ocrdma_verbs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c
+++ b/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c
@@ -442,9 +442,9 @@ static void ocrdma_dealloc_ucontext_pd(s
 		pr_err("%s(%d) Freeing in use pdid=0x%x.\n",
 		       __func__, dev->id, pd->id);
 	}
-	kfree(uctx->cntxt_pd);
 	uctx->cntxt_pd = NULL;
 	_ocrdma_dealloc_pd(dev, pd);
+	kfree(pd);
 }
 
 static struct ocrdma_pd *ocrdma_get_ucontext_pd(struct ocrdma_ucontext *uctx)