| Message ID | 20191008201154.10650-1-jesus.manzano@galgus.net |
|---|---|
| State | Superseded |
| Headers | show |
| Series | wpa_supplicant: Fix arithmetic on void pointer | expand |
On Tue, 2019-10-08 at 22:11 +0200, Jesus Fernandez Manzano wrote: > When using void pointers in calculations, the behaviour is undefined. > Arithmetic operations on 'void *' is a GNU C extension, > which defines the 'sizeof(void)' to be 1. I'm curious, do you have a compiler that tells you about this or something? Or how else did you find it? johannes
Adding -Wpointer-arith to CFLAGS does the trick for gcc and clang. Markus On 10/8/19 10:20 PM, Johannes Berg wrote: > On Tue, 2019-10-08 at 22:11 +0200, Jesus Fernandez Manzano wrote: >> When using void pointers in calculations, the behaviour is undefined. >> Arithmetic operations on 'void *' is a GNU C extension, >> which defines the 'sizeof(void)' to be 1. > I'm curious, do you have a compiler that tells you about this or > something? Or how else did you find it? > > johannes > > > _______________________________________________ > Hostap mailing list > Hostap@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/hostap
As Markus said, using GCC with -Wpointer-arith tells you the issue. Jesus.
I'm sending a v2 version to fix a problem with signedness. Jesus.
diff --git a/wpa_supplicant/wpa_priv.c b/wpa_supplicant/wpa_priv.c index b3ad45eca..f59788d38 100644 --- a/wpa_supplicant/wpa_priv.c +++ b/wpa_supplicant/wpa_priv.c @@ -598,7 +598,7 @@ static void wpa_priv_cmd_l2_send(struct wpa_priv_interface *iface, } dst_addr = buf; - os_memcpy(&proto, buf + ETH_ALEN, 2); + os_memcpy(&proto, (char *) buf + ETH_ALEN, 2); if (!wpa_priv_allowed_l2_proto(proto)) { wpa_printf(MSG_DEBUG, "Refused l2_packet send for ethertype " @@ -607,7 +607,7 @@ static void wpa_priv_cmd_l2_send(struct wpa_priv_interface *iface, } res = l2_packet_send(iface->l2[idx], dst_addr, proto, - buf + ETH_ALEN + 2, len - ETH_ALEN - 2); + (char *) buf + ETH_ALEN + 2, len - ETH_ALEN - 2); wpa_printf(MSG_DEBUG, "L2 send[idx=%d]: res=%d", idx, res); }
When using void pointers in calculations, the behaviour is undefined. Arithmetic operations on 'void *' is a GNU C extension, which defines the 'sizeof(void)' to be 1. This change improves portability of the code. Signed-off-by: Jesus Fernandez Manzano <jesus.manzano@galgus.net> --- wpa_supplicant/wpa_priv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)