mtd: rawnand: intel: Fix potential buffer overflow in probe

ebu_nand_probe() read the value of u32 variable "cs" from the device
firmware description and used it as the index for array ebu_host->cs
that can contain MAX_CS (2) elements at most. That could result in
a buffer overflow and various bad consequences later.

Fix the potential buffer overflow by restricting values of "cs" with
MAX_CS in probe.

Found by Linux Driver Verification project (linuxtesting.org).

Fixes: 0b1039f016e8 ("mtd: rawnand: Add NAND controller support on Intel LGM SoC")
Signed-off-by: Evgeny Novikov <novikov@ispras.ru>
Co-developed-by: Kirill Shilimanov <kirill.shilimanov@huawei.com>
Signed-off-by: Kirill Shilimanov <kirill.shilimanov@huawei.com>
Co-developed-by: Anton Vasilyev <vasilyev@ispras.ru>
Signed-off-by: Anton Vasilyev <vasilyev@ispras.ru>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210903082653.16441-1-novikov@ispras.ru

diff --git a/drivers/mtd/nand/raw/intel-nand-controller.c b/drivers/mtd/nand/raw/intel-nand-controller.c
index b9784f3..7c1c80d 100644 (file)
--- a/drivers/mtd/nand/raw/intel-nand-controller.c
+++ b/drivers/mtd/nand/raw/intel-nand-controller.c
@@ -609,6 +609,11 @@ static int ebu_nand_probe(struct platform_device *pdev)
                dev_err(dev, "failed to get chip select: %d\n", ret);
                return ret;
        }
+       if (cs >= MAX_CS) {
+               dev_err(dev, "got invalid chip select: %d\n", cs);
+               return -EINVAL;
+       }
+
        ebu_host->cs_num = cs;
 
        resname = devm_kasprintf(dev, GFP_KERNEL, "nand_cs%d", cs);