From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Date: Thu, 16 Jan 2020 16:58:47 +0000 Subject: [PATCH AUTOSEL 4.19 289/671] scsi: target/core: Fix a race condition in the LUN lookup code Message-Id: <20200116170509.12787-26-sashal@kernel.org> List-Id: References: <20200116170509.12787-1-sashal@kernel.org> In-Reply-To: <20200116170509.12787-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Bart Van Assche , Mike Christie , Christoph Hellwig , Hannes Reinecke , Nicholas Bellinger , "Martin K . Petersen" , Sasha Levin , linux-scsi@vger.kernel.org, target-devel@vger.kernel.org From: Bart Van Assche [ Upstream commit 63f7479439c95bcd49b7dd4af809862c316c71a3 ] The rcu_dereference(deve->se_lun) expression occurs twice in the LUN lookup functions. Since these expressions are not serialized against deve->se_lun assignments each of these expressions may yield a different result. Avoid that the wrong LUN pointer is stored in se_cmd by reading deve->se_lun only once. Cc: Mike Christie Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Nicholas Bellinger Fixes: 29a05deebf6c ("target: Convert se_node_acl->device_list[] to RCU hlist") # v4.10 Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- drivers/target/target_core_device.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index e9ff2a7c0c0e..22e97a93728d 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -85,7 +85,7 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun) goto out_unlock; } - se_cmd->se_lun = rcu_dereference(deve->se_lun); + se_cmd->se_lun = se_lun; se_cmd->pr_res_key = deve->pr_res_key; se_cmd->orig_fe_lun = unpacked_lun; se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD; @@ -176,7 +176,7 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd, u64 unpacked_lun) goto out_unlock; } - se_cmd->se_lun = rcu_dereference(deve->se_lun); + se_cmd->se_lun = se_lun; se_cmd->pr_res_key = deve->pr_res_key; se_cmd->orig_fe_lun = unpacked_lun; se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD; -- 2.20.1