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.
Signed-off-by: Markus Mayer <[email protected]>
---
This patch was prepared in response to https://lkml.org/lkml/2020/8/18/505.
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 81abc4a98a27..a986a849f58e 100644
--- a/drivers/memory/brcmstb_dpfe.c
+++ b/drivers/memory/brcmstb_dpfe.c
@@ -190,11 +190,6 @@ 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 * const 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;
@@ -446,7 +455,7 @@ 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
On 8/20/2020 6:03 PM, 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.
>
> 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]>
(Colin, was there a specific coverity ID you wanted to use?)
--
Florian
Hi Markus,
I love your patch! Perhaps something to improve:
[auto build test WARNING on linus/master]
[also build test WARNING on v5.9-rc1 next-20200820]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Markus-Mayer/memory-brcmstb_dpfe-fix-array-index-out-of-bounds/20200821-090533
base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git da2968ff879b9e74688cdc658f646971991d2c56
config: arm-defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
>> drivers/memory/brcmstb_dpfe.c:305:8: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
305 | static const char * const get_error_text(unsigned int i)
| ^~~~~
# https://github.com/0day-ci/linux/commit/a2de88715f98369b7e4478457a6455c3e2c72725
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Markus-Mayer/memory-brcmstb_dpfe-fix-array-index-out-of-bounds/20200821-090533
git checkout a2de88715f98369b7e4478457a6455c3e2c72725
vim +305 drivers/memory/brcmstb_dpfe.c
304
> 305 static const char * const get_error_text(unsigned int i)
306 {
307 static const char * const error_text[] = {
308 "Success", "Header code incorrect",
309 "Unknown command or argument", "Incorrect checksum",
310 "Malformed command", "Timed out", "Unknown error",
311 };
312
313 if (unlikely(i >= ARRAY_SIZE(error_text)))
314 i = ARRAY_SIZE(error_text) - 1;
315
316 return error_text[i];
317 }
318
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]
On Thu, Aug 20, 2020 at 06:03:33PM -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.
>
> Signed-off-by: Markus Mayer <[email protected]>
> ---
>
> This patch was prepared in response to https://lkml.org/lkml/2020/8/18/505.
>
> 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 81abc4a98a27..a986a849f58e 100644
> --- a/drivers/memory/brcmstb_dpfe.c
> +++ b/drivers/memory/brcmstb_dpfe.c
> @@ -190,11 +190,6 @@ 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 * const get_error_text(unsigned int i)
The pointer itself is returned by value and you cannot return a const
value. I mean, you can but it does not have an effect. Only pointed
memory should be const (const const char*).
Best regards,
Krzysztof
> +{
> + 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;
> @@ -446,7 +455,7 @@ 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
>
On Thu, 20 Aug 2020 at 22:40, Krzysztof Kozlowski <[email protected]> wrote:
>
> On Thu, Aug 20, 2020 at 06:03:33PM -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.
> >
> > Signed-off-by: Markus Mayer <[email protected]>
> > ---
> >
> > This patch was prepared in response to https://lkml.org/lkml/2020/8/18/505.
> >
> > 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 81abc4a98a27..a986a849f58e 100644
> > --- a/drivers/memory/brcmstb_dpfe.c
> > +++ b/drivers/memory/brcmstb_dpfe.c
> > @@ -190,11 +190,6 @@ 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 * const get_error_text(unsigned int i)
>
> The pointer itself is returned by value and you cannot return a const
> value. I mean, you can but it does not have an effect. Only pointed
> memory should be const (const const char*).
v2 is on the way.
Regards,
-Markus
> > +{
> > + 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;
> > @@ -446,7 +455,7 @@ 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
> >