2020-08-22 21:31:49

by Markus Mayer

Subject: [PATCH v3] memory: brcmstb_dpfe: fix array index out of bounds

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.

This patch was prepared in response to
https://lkml.org/lkml/2020/8/18/505.

Signed-off-by: Markus Mayer <[email protected]>
Acked-by: Florian Fainelli <[email protected]>
Fixes: 2f330caff577 ("memory: brcmstb: Add driver for DPFE")
Reported-by: Colin Ian King <[email protected]>
---

Changes since v2:
- Added "Fixes:" and "Reported-by:"
- Fixed "From" address
- No changes to the code

Changes since v1:
- Added link of the coverity report to the commit message.
- Added Florian's ack.
- Removed second "const" from get_error_text() return type
(thanks to the kernel test robot).

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 e08528b12cbd..dcf50bb8dd69 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 */
@@ -695,7 +704,7 @@ 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;
}
--
2.17.1

2020-08-22 21:55:09

by Krzysztof Kozlowski

Subject: Re: [PATCH v3] memory: brcmstb_dpfe: fix array index out of bounds

On Sat, Aug 22, 2020 at 01:50:00PM -0700, Markus Mayer wrote:
> 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.
>
> This patch was prepared in response to
> https://lkml.org/lkml/2020/8/18/505.
>
> Signed-off-by: Markus Mayer <[email protected]>
> Acked-by: Florian Fainelli <[email protected]>
> Fixes: 2f330caff577 ("memory: brcmstb: Add driver for DPFE")
> Reported-by: Colin Ian King <[email protected]>
> ---
>
> Changes since v2:
> - Added "Fixes:" and "Reported-by:"
> - Fixed "From" address
> - No changes to the code
>
> Changes since v1:
> - Added link of the coverity report to the commit message.
> - Added Florian's ack.
> - Removed second "const" from get_error_text() return type
> (thanks to the kernel test robot).
>
> drivers/memory/brcmstb_dpfe.c | 23 ++++++++++++++++-------
> 1 file changed, 16 insertions(+), 7 deletions(-)

"From" and SoB look good now.

Thanks, applied.

Best regards,
Krzysztof