Re: [bug report] RDMA/rxe: Replace pr_xxx by rxe_dbg_xxx in rxe_mr.c

[Jason Gunthorpe <jgg@ziepe.ca>]

On Fri, Nov 18, 2022 at 06:00:53PM +0300, Dan Carpenter wrote:
> Hello Bob Pearson,
> 
> This is a semi-automatic email about new static checker warnings.
> 
> The patch 2778b72b1df0: "RDMA/rxe: Replace pr_xxx by rxe_dbg_xxx in 
> rxe_mr.c" from Nov 3, 2022, leads to the following Smatch complaint:
> 
>     drivers/infiniband/sw/rxe/rxe_mr.c:527 rxe_invalidate_mr()
>     error: we previously assumed 'mr' could be null (see line 526)
> 
> drivers/infiniband/sw/rxe/rxe_mr.c
>    525		mr = rxe_pool_get_index(&rxe->mr_pool, key >> 8);
>    526		if (!mr) {
>                     ^^^
> "mr" is NULL.
> 
>    527			rxe_dbg_mr(mr, "No MR for key %#x\n", key);
>                                    ^^
> Dereference.
> 
>    528			ret = -EINVAL;
>    529			goto err;

I fixed it with this:

From 70c06ea1b57344599230e63d8fe5892f41c94116 Mon Sep 17 00:00:00 2001
From: Jason Gunthorpe <jgg@nvidia.com>
Date: Tue, 22 Nov 2022 15:37:39 -0400
Subject: [PATCH] RDMA/rxe: Do not NULL deref on debugging failure path

Correct the mistake, mr is obviously NULL in this code path.

Fixes: 2778b72b1df0 ("RDMA/rxe: Replace pr_xxx by rxe_dbg_xxx in rxe_mr.c")
Link: https://lore.kernel.org/r/Y3eeJW0AdyJYhYyQ@kili
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/infiniband/sw/rxe/rxe_mr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
index b1423000e4bcda..b7c9ff1ddf0e14 100644
--- a/drivers/infiniband/sw/rxe/rxe_mr.c
+++ b/drivers/infiniband/sw/rxe/rxe_mr.c
@@ -519,7 +519,7 @@ int rxe_invalidate_mr(struct rxe_qp *qp, u32 key)
 
 	mr = rxe_pool_get_index(&rxe->mr_pool, key >> 8);
 	if (!mr) {
-		rxe_dbg_mr(mr, "No MR for key %#x\n", key);
+		rxe_dbg_qp(qp, "No MR for key %#x\n", key);
 		ret = -EINVAL;
 		goto err;
 	}
-- 
2.38.1