2011-07-21 07:22:19

by Radoslaw Jablonski

Subject: [PATCH obexd] Fix writing out of bounds in add_slash func

diff --git a/plugins/vcard.c b/plugins/vcard.c
index b997fc4..a6eb5f5 100644
--- a/plugins/vcard.c
+++ b/plugins/vcard.c
@@ -101,27 +101,41 @@ static void add_slash(char *dest, const char *src, int len_max, int len)
{
int i, j;

- for (i = 0, j = 0; i < len && j < len_max; i++, j++) {
+ for (i = 0, j = 0; i < len && j < len_max - 1; i++, j++) {
+ /* filling dest buffer - last field need to be reserved
+ * for '\0'*/
switch (src[i]) {
case '\n':
+ if (j == len_max - 2)
+ /* not enough space in the buffer to put char
+ * preceded with escaping sequence */
+ goto done;
+
dest[j++] = '\\';
dest[j] = 'n';
break;
case '\r':
+ if (j == len_max - 2)
+ goto done;
+
dest[j++] = '\\';
dest[j] = 'r';
break;
case '\\':
case ';':
case ',':
+ if (j == len_max - 2)
+ goto done;
+
dest[j++] = '\\';
default:
dest[j] = src[i];
break;
}
}
+
+done:
dest[j] = 0;
- return;
}

static void get_escaped_fields(char **fields, ...)
--
1.7.0.4

2011-07-26 11:25:16

by Johan Hedberg

Subject: Re: [PATCH obexd] Fix writing out of bounds in add_slash func

Hi Radek,

On Thu, Jul 21, 2011, Radoslaw Jablonski wrote:
> diff --git a/plugins/vcard.c b/plugins/vcard.c
> index b997fc4..a6eb5f5 100644
> --- a/plugins/vcard.c
> +++ b/plugins/vcard.c
> @@ -101,27 +101,41 @@ static void add_slash(char *dest, const char *src, int len_max, int len)
> {
> int i, j;
>
> - for (i = 0, j = 0; i < len && j < len_max; i++, j++) {
> + for (i = 0, j = 0; i < len && j < len_max - 1; i++, j++) {
> + /* filling dest buffer - last field need to be reserved
> + * for '\0'*/
> switch (src[i]) {
> case '\n':
> + if (j == len_max - 2)
> + /* not enough space in the buffer to put char
> + * preceded with escaping sequence */
> + goto done;

I think it'd be more robust and clear that you're testing for an upper
limit to have a > or >= comparison here and in the other places, e.g.
if (j + 2 >= len_max)

> +done:
> dest[j] = 0;
> - return;
> }

The return statement removal is a code cleanup which should be in its
own patch.

Johan