From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Tue, 9 Jan 2018 20:03:46 +0000 (+0300)
Subject: IB/hfi1: Prevent a NULL dereference
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=57194fa763bfa1a0908f30d4c77835beaa118fcb;p=linux.git

IB/hfi1: Prevent a NULL dereference

In the original code, we set "fd->uctxt" to NULL and then dereference it
which will cause an Oops.

Fixes: f2a3bc00a03c ("IB/hfi1: Protect context array set/clear with spinlock")
Cc: <stable@vger.kernel.org> # 4.14.x
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
---

diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c
index 7750a9c38b066..1df7da47f4317 100644
--- a/drivers/infiniband/hw/hfi1/file_ops.c
+++ b/drivers/infiniband/hw/hfi1/file_ops.c
@@ -763,11 +763,11 @@ static int complete_subctxt(struct hfi1_filedata *fd)
 	}
 
 	if (ret) {
-		hfi1_rcd_put(fd->uctxt);
-		fd->uctxt = NULL;
 		spin_lock_irqsave(&fd->dd->uctxt_lock, flags);
 		__clear_bit(fd->subctxt, fd->uctxt->in_use_ctxts);
 		spin_unlock_irqrestore(&fd->dd->uctxt_lock, flags);
+		hfi1_rcd_put(fd->uctxt);
+		fd->uctxt = NULL;
 	}
 
 	return ret;