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SubjectRe: [PATCH] libertas: Avoid reading past end of buffer
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On Tue, 2017-05-09 at 16:23 -0700, Kees Cook wrote:
> Using memcpy() from a string that is shorter than the length copied means
> the destination buffer is being filled with arbitrary data from the kernel
> rodata segment. Instead, use strncpy() which will fill the trailing bytes
> with zeros. Additionally adjust indentation to keep checkpatch.pl happy.
>
> This was found with the future CONFIG_FORTIFY_SOURCE feature.
[]
> diff --git a/drivers/net/wireless/marvell/libertas/mesh.c b/drivers/net/wireless/marvell/libertas/mesh.c
[]
> @@ -1177,9 +1177,9 @@ void lbs_mesh_ethtool_get_strings(struct net_device *dev,
> 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);
> + strncpy(s + i * ETH_GSTRING_LEN,
> + mesh_stat_strings[i],
> + ETH_GSTRING_LEN);
> }

The better solution is to declare
mesh_stat_strings in in the normal way

---
drivers/net/wireless/marvell/libertas/mesh.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas/mesh.c b/drivers/net/wireless/marvell/libertas/mesh.c
index d0c881dd5846..a535e7f48d2d 100644
--- a/drivers/net/wireless/marvell/libertas/mesh.c
+++ b/drivers/net/wireless/marvell/libertas/mesh.c
@@ -1108,15 +1108,15 @@ void lbs_mesh_set_txpd(struct lbs_private *priv,
* Ethtool related
*/

-static const char * const mesh_stat_strings[] = {
- "drop_duplicate_bcast",
- "drop_ttl_zero",
- "drop_no_fwd_route",
- "drop_no_buffers",
- "fwded_unicast_cnt",
- "fwded_bcast_cnt",
- "drop_blind_table",
- "tx_failed_cnt"
+static const char mesh_stat_strings[][ETH_GSTRING_LEN] = {
+ "drop_duplicate_bcast",
+ "drop_ttl_zero",
+ "drop_no_fwd_route",
+ "drop_no_buffers",
+ "fwded_unicast_cnt",
+ "fwded_bcast_cnt",
+ "drop_blind_table",
+ "tx_failed_cnt",
};

void lbs_mesh_ethtool_get_stats(struct net_device *dev,
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