[PATCH 5.14 666/849] mtd: rawnand: intel: Fix potential buffer overflow in probe

From: Evgeny Novikov <redacted>

[ Upstream commit 46a0dc10fb32bec3e765e51bf71fbc070dc77ca3 ]

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 <redacted>
Co-developed-by: Kirill Shilimanov <redacted>
Signed-off-by: Kirill Shilimanov <redacted>
Co-developed-by: Anton Vasilyev <redacted>
Signed-off-by: Anton Vasilyev <redacted>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210903082653.16441-1-novikov@ispras.ru (local)
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/mtd/nand/raw/intel-nand-controller.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/mtd/nand/raw/intel-nand-controller.c b/drivers/mtd/nand/raw/intel-nand-controller.c
index 29e8a546dcd60..e8476cd5147fe 100644
--- 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);

-- 
2.33.0