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    Subject[PATCH 5.9 587/757] memory: brcmstb_dpfe: fix array index out of bounds
    Date
    From: Markus Mayer <mmayer@broadcom.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@canonical.com>
    Signed-off-by: Markus Mayer <mmayer@broadcom.com>
    Acked-by: Florian Fainelli <f.fainelli@gmail.com>
    Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.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


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