linux-kernel - [PATCH 5.9 587/757] memory: brcmstb_dpfe: fix array index out of bounds

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Message-Id: <20201027135518.067024639@linuxfoundation.org>
Date:   Tue, 27 Oct 2020 14:53:57 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Colin Ian King <colin.king@...onical.com>,
        Markus Mayer <mmayer@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 587/757] memory: brcmstb_dpfe: fix array index out of bounds

From: Markus Mayer <mmayer@...adcom.com>

[ Upstream commit f42ae4bbf94c15aa720afb9d176ecbfe140d792e ]

We would overrun the error_text array if we hit a TIMEOUT condition,
because we were using the error code "ETIMEDOUT" (which is 110) as an
array index.

We fix the problem by correcting the array index and by providing a
function to retrieve error messages rather than accessing the array
directly. The function includes a bounds check that prevents the array
from being overrun.

Link: https://lore.kernel.org/linux-arm-kernel/38d00022-730c-948a-917c-d86382df8cb9@canonical.com/
Link: https://lore.kernel.org/r/20200822205000.15841-1-mmayer@broadcom.com
Fixes: 2f330caff577 ("memory: brcmstb: Add driver for DPFE")
Reported-by: Colin Ian King <colin.king@...onical.com>
Signed-off-by: Markus Mayer <mmayer@...adcom.com>
Acked-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/memory/brcmstb_dpfe.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/memory/brcmstb_dpfe.c b/drivers/memory/brcmstb_dpfe.c
index 60e8633b11758..ddff687c79eaa 100644
--- a/drivers/memory/brcmstb_dpfe.c
+++ b/drivers/memory/brcmstb_dpfe.c
@@ -188,11 +188,6 @@ struct brcmstb_dpfe_priv {
 	struct mutex lock;
 };
 
-static const char * const error_text[] = {
-	"Success", "Header code incorrect", "Unknown command or argument",
-	"Incorrect checksum", "Malformed command", "Timed out",
-};
-
 /*
  * Forward declaration of our sysfs attribute functions, so we can declare the
  * attribute data structures early.
@@ -307,6 +302,20 @@ static const struct dpfe_api dpfe_api_v3 = {
 	},
 };
 
+static const char *get_error_text(unsigned int i)
+{
+	static const char * const error_text[] = {
+		"Success", "Header code incorrect",
+		"Unknown command or argument", "Incorrect checksum",
+		"Malformed command", "Timed out", "Unknown error",
+	};
+
+	if (unlikely(i >= ARRAY_SIZE(error_text)))
+		i = ARRAY_SIZE(error_text) - 1;
+
+	return error_text[i];
+}
+
 static bool is_dcpu_enabled(struct brcmstb_dpfe_priv *priv)
 {
 	u32 val;
@@ -445,7 +454,7 @@ static int __send_command(struct brcmstb_dpfe_priv *priv, unsigned int cmd,
 	}
 	if (resp != 0) {
 		mutex_unlock(&priv->lock);
-		return -ETIMEDOUT;
+		return -ffs(DCPU_RET_ERR_TIMEDOUT);
 	}
 
 	/* Compute checksum over the message */
@@ -691,7 +700,7 @@ static ssize_t generic_show(unsigned int command, u32 response[],
 
 	ret = __send_command(priv, command, response);
 	if (ret < 0)
-		return sprintf(buf, "ERROR: %s\n", error_text[-ret]);
+		return sprintf(buf, "ERROR: %s\n", get_error_text(-ret));
 
 	return 0;
 }
-- 
2.25.1