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From:   Simon Horman <horms@kernel.org>
Date:   Thu, 25 May 2023 12:52:58 +0200
Subject: [PATCH net] ice: Don't dereference NULL in ice_gns_read error path
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Message-Id: <20230525-null-ice-v1-1-30d10557b91e@kernel.org>
To:     Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>
Cc:     Jakub Kicinski <kuba@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Karol Kolacinski <karol.kolacinski@intel.com>,
        Sudhansu Sekhar Mishra <sudhansu.mishra@intel.com>,
        Dan Carpenter <dan.carpenter@linaro.org>,
        intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Precedence: bulk

If pf is NULL in ice_gns_read() then it will be dereferenced
in the error path by a call to dev_dbg(ice_pf_to_dev(pf), ...).

Avoid this by simply returning in this case.
If logging is desired an alternate approach might be to
use pr_err() before returning.

Flagged by Smatch as:

  .../ice_gnss.c:196 ice_gnss_read() error: we previously assumed 'pf' could be null (see line 131)

Fixes: 43113ff73453 ("ice: add TTY for GNSS module for E810T device")
Signed-off-by: Simon Horman <horms@kernel.org>
---
 drivers/net/ethernet/intel/ice/ice_gnss.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_gnss.c b/drivers/net/ethernet/intel/ice/ice_gnss.c
index 2ea8a2b11bcd..3d0663840aa1 100644
--- a/drivers/net/ethernet/intel/ice/ice_gnss.c
+++ b/drivers/net/ethernet/intel/ice/ice_gnss.c
@@ -128,12 +128,7 @@ static void ice_gnss_read(struct kthread_work *work)
 	int err = 0;
 
 	pf = gnss->back;
-	if (!pf) {
-		err = -EFAULT;
-		goto exit;
-	}
-
-	if (!test_bit(ICE_FLAG_GNSS, pf->flags))
+	if (!pf || !test_bit(ICE_FLAG_GNSS, pf->flags))
 		return;
 
 	hw = &pf->hw;
@@ -191,7 +186,6 @@ static void ice_gnss_read(struct kthread_work *work)
 	free_page((unsigned long)buf);
 requeue:
 	kthread_queue_delayed_work(gnss->kworker, &gnss->read_work, delay);
-exit:
 	if (err)
 		dev_dbg(ice_pf_to_dev(pf), "GNSS failed to read err=%d\n", err);
 }