2020-03-12 14:42:29

by Gabriel Ravier

Subject: [PATCH v2] gpio-hammer: Avoid potential overflow in main

If '-o' was used more than 64 times in a single invocation of gpio-hammer,
this could lead to an overflow of the 'lines' array. This commit fixes
this by avoiding the overflow and giving a proper diagnostic back to the
user

Signed-off-by: Gabriel Ravier <[email protected]>
---
tools/gpio/gpio-hammer.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/tools/gpio/gpio-hammer.c b/tools/gpio/gpio-hammer.c
index 0e0060a6e..d0be21af1 100644
--- a/tools/gpio/gpio-hammer.c
+++ b/tools/gpio/gpio-hammer.c
@@ -135,7 +135,14 @@ int main(int argc, char **argv)
device_name = optarg;
break;
case 'o':
- lines[i] = strtoul(optarg, NULL, 10);
+ /*
+ * Avoid overflow. Do not immediately error, we want to
+ * be able to accurately report on the amount of times
+ *'-o' was given to give an accurate error message
+ */
+ if (i < GPIOHANDLES_MAX)
+ lines[i] = strtoul(optarg, NULL, 10);
+
i++;
break;
case '?':
@@ -143,6 +150,14 @@ int main(int argc, char **argv)
return -1;
}
}
+
+ if (i >= GPIOHANDLES_MAX) {
+ fprintf(stderr,
+ "Only %d occurences of '-o' are allowed, %d were found\n",
+ GPIOHANDLES_MAX, i + 1);
+ return -1;
+ }
+
nlines = i;

if (!device_name || !nlines) {
--
2.24.1

2020-03-12 14:51:00

by Gabriel Ravier

Subject: Re: [PATCH v2] gpio-hammer: Avoid potential overflow in main

On 3/12/20 3:40 PM, Gabriel Ravier wrote:
> If '-o' was used more than 64 times in a single invocation of gpio-hammer,
> this could lead to an overflow of the 'lines' array. This commit fixes
> this by avoiding the overflow and giving a proper diagnostic back to the
> user
>
> Signed-off-by: Gabriel Ravier <[email protected]>
> ---
> tools/gpio/gpio-hammer.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/tools/gpio/gpio-hammer.c b/tools/gpio/gpio-hammer.c
> index 0e0060a6e..d0be21af1 100644
> --- a/tools/gpio/gpio-hammer.c
> +++ b/tools/gpio/gpio-hammer.c
> @@ -135,7 +135,14 @@ int main(int argc, char **argv)
> device_name = optarg;
> break;
> case 'o':
> - lines[i] = strtoul(optarg, NULL, 10);
> + /*
> + * Avoid overflow. Do not immediately error, we want to
> + * be able to accurately report on the amount of times
> + *'-o' was given to give an accurate error message
> + */
> + if (i < GPIOHANDLES_MAX)
> + lines[i] = strtoul(optarg, NULL, 10);
> +
> i++;
> break;
> case '?':
> @@ -143,6 +150,14 @@ int main(int argc, char **argv)
> return -1;
> }
> }
> +
> + if (i >= GPIOHANDLES_MAX) {
> + fprintf(stderr,
> + "Only %d occurences of '-o' are allowed, %d were found\n",
> + GPIOHANDLES_MAX, i + 1);
> + return -1;
> + }
> +
> nlines = i;
>
> if (!device_name || !nlines) {

Just noticed that there isn't a space before the "'-o'" in the third
line of the explanatory comment in the first part of the patch, will
send a third version of the patch with a space before the "'-o'"