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From:   Ivan Vecera <ivecera@redhat.com>
To:     netdev@vger.kernel.org
Cc:     poros@redhat.com, mschmidt@redhat.com, jacob.e.keller@intel.com,
        Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Brett Creeley <brett.creeley@intel.com>,
        intel-wired-lan@lists.osuosl.org (moderated list:INTEL ETHERNET DRIVERS),
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH net v2] ice: Fix incorrect locking in ice_vc_process_vf_msg()
Date:   Fri,  1 Apr 2022 12:40:52 +0200
Message-Id: <20220401104052.1711721-1-ivecera@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Usage of mutex_trylock() in ice_vc_process_vf_msg() is incorrect
because message sent from VF is ignored and never processed.

Use mutex_lock() instead to fix the issue. It is safe because this
mutex is used to prevent races between VF related NDOs and
handlers processing request messages from VF and these handlers
are running in ice_service_task() context. Additionally move this
mutex lock prior ice_vc_is_opcode_allowed() call to avoid potential
races during allowlist acccess.

Fixes: e6ba5273d4ed ("ice: Fix race conditions between virtchnl handling and VF ndo ops")
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
 drivers/net/ethernet/intel/ice/ice_virtchnl.c | 21 +++++++------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_virtchnl.c b/drivers/net/ethernet/intel/ice/ice_virtchnl.c
index 3f1a63815bac..a465f3743ffc 100644
--- a/drivers/net/ethernet/intel/ice/ice_virtchnl.c
+++ b/drivers/net/ethernet/intel/ice/ice_virtchnl.c
@@ -3642,14 +3642,6 @@ void ice_vc_process_vf_msg(struct ice_pf *pf, struct ice_rq_event_info *event)
 			err = -EINVAL;
 	}
 
-	if (!ice_vc_is_opcode_allowed(vf, v_opcode)) {
-		ice_vc_send_msg_to_vf(vf, v_opcode,
-				      VIRTCHNL_STATUS_ERR_NOT_SUPPORTED, NULL,
-				      0);
-		ice_put_vf(vf);
-		return;
-	}
-
 error_handler:
 	if (err) {
 		ice_vc_send_msg_to_vf(vf, v_opcode, VIRTCHNL_STATUS_ERR_PARAM,
@@ -3660,12 +3652,13 @@ void ice_vc_process_vf_msg(struct ice_pf *pf, struct ice_rq_event_info *event)
 		return;
 	}
 
-	/* VF is being configured in another context that triggers a VFR, so no
-	 * need to process this message
-	 */
-	if (!mutex_trylock(&vf->cfg_lock)) {
-		dev_info(dev, "VF %u is being configured in another context that will trigger a VFR, so there is no need to handle this message\n",
-			 vf->vf_id);
+	mutex_lock(&vf->cfg_lock);
+
+	if (!ice_vc_is_opcode_allowed(vf, v_opcode)) {
+		ice_vc_send_msg_to_vf(vf, v_opcode,
+				      VIRTCHNL_STATUS_ERR_NOT_SUPPORTED, NULL,
+				      0);
+		mutex_unlock(&vf->cfg_lock);
 		ice_put_vf(vf);
 		return;
 	}
-- 
2.35.1