Re: [PATCH] libertas: Avoid reading past end of buffer

From: Joe Perches
Date: Wed May 10 2017 - 19:05:28 EST


On Wed, 2017-05-10 at 12:24 -0700, Kees Cook wrote:
> Using memcpy() from a string that is shorter than the length copied means
[]
> diff --git a/drivers/net/wireless/marvell/libertas/mesh.c b/drivers/net/wireless/marvell/libertas/mesh.c
[]
> @@ -1170,17 +1170,11 @@ int lbs_mesh_ethtool_get_sset_count(struct net_device *dev, int sset)
> void lbs_mesh_ethtool_get_strings(struct net_device *dev,
> uint32_t stringset, uint8_t *s)
> {
> - int i;
> -
> lbs_deb_enter(LBS_DEB_ETHTOOL);
>
> switch (stringset) {
> case ETH_SS_STATS:
> - for (i = 0; i < MESH_STATS_NUM; i++) {
> - memcpy(s + i * ETH_GSTRING_LEN,
> - mesh_stat_strings[i],
> - ETH_GSTRING_LEN);
> - }
> + memcpy(s, *mesh_stat_strings, sizeof(mesh_stat_strings));
> break;
> }
> lbs_deb_enter(LBS_DEB_ETHTOOL);

unrelated trivia:

lbs_deb_enter is used incorrectly here at
function exit as both enter and leave calls.

That type of copy/paste defect may be common.

$ git grep -w lbs_deb_enter | wc -l
148
$ git grep -w lbs_deb_leave | wc -l
71

One would expect these numbers to be the same.

Another option would be to delete all these
calls as ftrace function tracing works well.