christian.heimes <python-check...@python.org> wrote:
> Make sure that *really* no more than sizeof(ifr.ifr_name) chars are
> strcpy-ed to ifr.ifr_name and that the string is *always* NUL terminated. New
> code shouldn't use strcpy(), too. CID 719692
>
> files:
> Modules/socketmodule.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
>
> diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
> --- a/Modules/socketmodule.c
> +++ b/Modules/socketmodule.c
> @@ -1674,7 +1674,8 @@
> if (len == 0) {
> ifr.ifr_ifindex = 0;
> } else if (len < sizeof(ifr.ifr_name)) {
> - strcpy(ifr.ifr_name, PyBytes_AS_STRING(interfaceName));
> + strncpy(ifr.ifr_name, PyBytes_AS_STRING(interfaceName),
> sizeof(ifr.ifr_name));
> + ifr.ifr_name[(sizeof(ifr.ifr_name))-1] = '\0';
> if (ioctl(s->sock_fd, SIOCGIFINDEX, &ifr) < 0) {
> s->errorhandler();
> Py_DECREF(interfaceName);
I've trouble finding the overrun in the existing code. Previously:
We have:
1) len = PyBytes_GET_SIZE(interfaceName); (without NUL terminator)
At the point of strcpy() we have:
2) len < sizeof(ifr.ifr_name)
PyBytes_AS_STRING(interfaceName) always adds a NUL terminator, so:
3) len+1 <= sizeof(ifr.ifr_name)
4) strcpy(ifr.ifr_name, PyBytes_AS_STRING(interfaceName)) will not overrun
ifr.ifr_name and ifr.ifr_name is always NUL terminated.
So IMO the strcpy() was safe and the report is a false positive.
Stefan Krah
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