net: qlogic: qlcnic: Fix a NULL pointer dereference in qlcnic_83xx_add_rings()

zhou1615 · kuba-moo · commit e2dabc4f7e7b · 2021-12-01T18:51:36.000-08:00
In qlcnic_83xx_add_rings(), the indirect function of ahw->hw_ops->alloc_mbx_args will be called to allocate memory for cmd.req.arg, and there is a dereference of it in qlcnic_83xx_add_rings(), which could lead to a NULL pointer dereference on failure of the indirect function like qlcnic_83xx_alloc_mbx_args(). Fix this bug by adding a check of alloc_mbx_args(), this patch imitates the logic of mbx_cmd()'s failure handling. This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs. Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug. Builds with CONFIG_QLCNIC=m show no new warnings, and our static analyzer no longer warns about this code. Fixes: 7f96645 ("qlcnic: 83xx memory map and HW access routine") Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> Link: https://lore.kernel.org/r/20211130110848.109026-1-zhou1615@umn.edu Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c
@@ -1077,8 +1077,14 @@ static int qlcnic_83xx_add_rings(struct qlcnic_adapter *adapter)
 	sds_mbx_size = sizeof(struct qlcnic_sds_mbx);
 	context_id = recv_ctx->context_id;
 	num_sds = adapter->drv_sds_rings - QLCNIC_MAX_SDS_RINGS;
-	ahw->hw_ops->alloc_mbx_args(&cmd, adapter,
-				    QLCNIC_CMD_ADD_RCV_RINGS);
+	err = ahw->hw_ops->alloc_mbx_args(&cmd, adapter,
+					QLCNIC_CMD_ADD_RCV_RINGS);
+	if (err) {
+		dev_err(&adapter->pdev->dev,
+			"Failed to alloc mbx args %d\n", err);
+		return err;
+	}
+
 	cmd.req.arg[1] = 0 | (num_sds << 8) | (context_id << 16);
 
 	/* set up status rings, mbx 2-81 */
