net/qlcnic: Fix a use after free in qlcnic_83xx_get_minidump_template

In qlcnic_83xx_get_minidump_template, fw_dump->tmpl_hdr was freed by
vfree(). But unfortunately, it is used when extended is true.

Fixes: 7061b2bd ("qlogic: Deletion of unnecessary checks before two function calls")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qlcnic/qlcnic_minidump.c

@@ -1425,6 +1425,7 @@ void qlcnic_83xx_get_minidump_template(struct qlcnic_adapter *adapter)
 
 	if (fw_dump->tmpl_hdr == NULL || current_version > prev_version) {
 		vfree(fw_dump->tmpl_hdr);
+		fw_dump->tmpl_hdr = NULL;
 
 		if (qlcnic_83xx_md_check_extended_dump_capability(adapter))
 			extended = !qlcnic_83xx_extend_md_capab(adapter);
@@ -1443,6 +1444,8 @@ void qlcnic_83xx_get_minidump_template(struct qlcnic_adapter *adapter)
 			struct qlcnic_83xx_dump_template_hdr *hdr;
 
 			hdr = fw_dump->tmpl_hdr;
+			if (!hdr)
+				return;
 			hdr->drv_cap_mask = 0x1f;
 			fw_dump->cap_mask = 0x1f;
 			dev_info(&pdev->dev,