phy: ocelot-serdes: fix out-of-bounds read

This patchset aims to fix an out-of-bounds bug in
the phy-ocelot-serdes driver.

Currently, there is an out-of-bounds read on array ctrl->phys, once variable i reaches the maximum array size of SERDES_MAX in the for loop.

Quentin Schulz pointed out that SERDES_MAX is a valid value to index ctrl->phys. So, I updated SERDES_MAX to be SERDES6G_MAX + 1 in include/dt-bindings/phy/phy-ocelot-serdes.h.

Then I changed the condition in the for loop from
i <= SERDES_MAX to i < SERDES_MAX in order to
complete the fix.

The reason I'm sending this fix as series is because checkpatch reported an error when I first tried to integrate the whole solution into a singe patch. So, changes to dt-bindings should be sent as a separate patch.

Changes in v2:
- Send the whole series to Kishon Vijay Abraham I, so it can be taken into the PHY tree.
- Add Quentin's Reviewed-by to commit log in both patches.

Thanks!

Gustavo A. R. Silva (2):
dt-bindings: phy: Update SERDES_MAX to be SERDES_MAX + 1
phy: ocelot-serdes: fix out-of-bounds read

 drivers/phy/mscc/phy-ocelot-serdes.c        | 4 ++--
 include/dt-bindings/phy/phy-ocelot-serdes.h | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

2.7.4

SERDES_MAX is a valid value to index ctrl->phys in drivers/phy/mscc/phy-ocelot-serdes.c. But, currently, there is an out-of-bounds bug in the mentioned driver when reading from ctrl->phys, because the size of array ctrl->phys is SERDES_MAX.

Partially fix this by updating SERDES_MAX to be SERDES6G_MAX + 1.

Notice that this is the first part of the solution to the out-of-bounds bug mentioned above. Although this change is not dependent on any other one.

---
Changes in v2:
- Add Quentin's Reviewed-by to commit log.
- Add Rob's Acked-by to commit log.

 include/dt-bindings/phy/phy-ocelot-serdes.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index bd28f21..fe70ada 100644
@@ -7,6 +7,6 @@
 #define SERDES1G_MAX	SERDES1G(5)
 #define SERDES6G(x)	(SERDES1G_MAX + 1 + (x))
 #define SERDES6G_MAX	SERDES6G(2)
-#define SERDES_MAX	SERDES6G_MAX
+#define SERDES_MAX	(SERDES6G_MAX + 1)
 
 #endif

2.7.4

Currently, there is an out-of-bounds read on array ctrl->phys, once variable i reaches the maximum array size of SERDES_MAX in the for loop.

Fix this by changing the condition in the for loop from i <= SERDES_MAX to i < SERDES_MAX.

Addresses-Coverity-ID: 1473966 ("Out-of-bounds read")
Addresses-Coverity-ID: 1473959 ("Out-of-bounds read")

---
Changes in v2:
- Rebase and add Quentin's Reviewed-by to commit log.

 drivers/phy/mscc/phy-ocelot-serdes.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index b2be546..cbb49d9 100644
@@ -206,7 +206,7 @@ static struct phy *serdes_simple_xlate(struct device *dev,
 	port = args->args[0];
 	idx = args->args[1];
 
-	for (i = 0; i <= SERDES_MAX; i++) {
+	for (i = 0; i < SERDES_MAX; i++) {
 		struct serdes_macro *macro = phy_get_drvdata(ctrl->phys[i]);
 
 		if (idx != macro->idx)

@@ -260,7 +260,7 @@ static int serdes_probe(struct platform_device *pdev)
 	if (IS_ERR(ctrl->regs))
 		return PTR_ERR(ctrl->regs);
 
-	for (i = 0; i <= SERDES_MAX; i++) {
+	for (i = 0; i < SERDES_MAX; i++) {
 		ret = serdes_phy_create(ctrl, i, &ctrl->phys[i]);
 		if (ret)
 			return ret;

2.7.4