[PATCH] qed: fix qed_fill_link() error handling

From: Arnd Bergmann
Date: Mon May 30 2016 - 11:46:25 EST


gcc warns about qed_fill_link possibly accessing uninitialized data:

drivers/net/ethernet/qlogic/qed/qed_main.c: In function 'qed_fill_link':
drivers/net/ethernet/qlogic/qed/qed_main.c:1170:35: error: 'link_caps' may be used uninitialized in this function [-Werror=maybe-uninitialized]

While this warning is only about the specific case of CONFIG_QED_SRIOV
being disabled but the function getting called for a VF (which should
never happen), another possibility is that qed_mcp_get_*() fails without
returning data.

This rearranges the code so we bail out in either of the two cases
and print a warning instead of accessing the uninitialized data.

The qed_link_output structure remains untouched in this case, but
all callers first call memset() on it, so at least we are not leaking
stack data then.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/net/ethernet/qlogic/qed/qed_main.c | 45 ++++++++++++++++++++++++------
1 file changed, 36 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_main.c b/drivers/net/ethernet/qlogic/qed/qed_main.c
index 753064679bde..68f87a4f9316 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_main.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_main.c
@@ -1105,6 +1105,39 @@ static int qed_get_port_type(u32 media_type)
return port_type;
}

+static int qed_get_link_data(struct qed_hwfn *hwfn,
+ struct qed_mcp_link_params *params,
+ struct qed_mcp_link_state *link,
+ struct qed_mcp_link_capabilities *link_caps)
+{
+ void *p;
+
+ if (IS_ENABLED(CONFIG_QED_SRIOV) && !IS_PF(hwfn->cdev)) {
+ qed_vf_get_link_params(hwfn, params);
+ qed_vf_get_link_state(hwfn, link);
+ qed_vf_get_link_caps(hwfn, link_caps);
+
+ return 0;
+ }
+
+ p = qed_mcp_get_link_params(hwfn);
+ if (!p)
+ return -ENXIO;
+ memcpy(params, p, sizeof(*params));
+
+ p = qed_mcp_get_link_state(hwfn);
+ if (!p)
+ return -ENXIO;
+ memcpy(link, p, sizeof(*link));
+
+ p = qed_mcp_get_link_capabilities(hwfn);
+ if (!p)
+ return -ENXIO;
+ memcpy(link_caps, p, sizeof(*link_caps));
+
+ return 0;
+}
+
static void qed_fill_link(struct qed_hwfn *hwfn,
struct qed_link_output *if_link)
{
@@ -1116,15 +1149,9 @@ static void qed_fill_link(struct qed_hwfn *hwfn,
memset(if_link, 0, sizeof(*if_link));

/* Prepare source inputs */
- if (IS_PF(hwfn->cdev)) {
- memcpy(&params, qed_mcp_get_link_params(hwfn), sizeof(params));
- memcpy(&link, qed_mcp_get_link_state(hwfn), sizeof(link));
- memcpy(&link_caps, qed_mcp_get_link_capabilities(hwfn),
- sizeof(link_caps));
- } else {
- qed_vf_get_link_params(hwfn, &params);
- qed_vf_get_link_state(hwfn, &link);
- qed_vf_get_link_caps(hwfn, &link_caps);
+ if (qed_get_link_data(hwfn, &params, &link, &link_caps)) {
+ dev_warn(&hwfn->cdev->pdev->dev, "no link data available\n");
+ return;
}

/* Set the link parameters to pass to protocol driver */
--
2.7.0