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

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")

Fixes 51f6b410fc22 ("phy: add driver for Microsemi Ocelot SerDes muxing")

Signed-off-by Gustavo A. R. Silva <[email protected]>

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

drivers/phy/mscc/phy-ocelot-serdes.c +2 -2

index 8936abd..c4eee3a 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 (!ctrl->regs)
 		return -ENODEV;
 
-	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;

Signature · 1 line

2.7.4

Hi Gustavo,

Quoted 4 lines · Gustavo A. R. Silva

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.

Quoted 3 lines

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

Thanks for the heads up. However, as defined today, SERDES_MAX is a valid value so I need it in the iteration. There are two possible fixes though:

Either we let all the for loops as for (i = 0; i <= SERDES_MAX; i++) and define ctrl->phys as an array of size SERDES_MAX + 1.

Or we modify the for loops as for (i = 0; i < SERDES_MAX; i++) and we update SERDES_MAX in include/dt-bindings/phy/phy-ocelot-serdes.h to be SERDES6G_MAX + 1.

As you wish!