Matthew DeVore <matvore@xxxxxxxxxx> writes:
> url_decode_internal could have been tricked into reading past the length
> of the **query buffer if there are fewer than 2 characters after a % (in
> a null-terminated string, % would have to be the last character).
> Prevent this from happening by checking len before decoding the %
> sequence.
>
> Helped-by: René Scharfe <l.s.r@xxxxxx>
> Signed-off-by: Matthew DeVore <matvore@xxxxxxxxxx>
> ---
> url.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/url.c b/url.c
> index 25576c390b..9ea9d5611b 100644
> --- a/url.c
> +++ b/url.c
> @@ -39,21 +39,21 @@ static char *url_decode_internal(const char **query, int len,
> unsigned char c = *q;
>
> if (!c)
> break;
> if (stop_at && strchr(stop_at, c)) {
> q++;
> len--;
> break;
> }
>
> - if (c == '%') {
> + if (c == '%' && (len < 0 || len >= 3)) {
> int val = hex2chr(q + 1);
This made me wonder what happens when the caller sent -1 in len, but
hex2chr() stops on such a string with % plus one hexadecimal at the
end of the string, and we'd end up copying these two bytes one at a
time, which is what we want, so it is OK. And the rejection of %00
done in 2/2 follows the same codeflow here, which is quite straight
forward.
Nice.
> if (0 <= val) {
> strbuf_addch(out, val);
> q += 3;
> len -= 3;
> continue;
> }
> }
>
> if (decode_plus && c == '+')
