bna: ethtool: Avoid reading past end of buffer

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.

This was found with the future CONFIG_FORTIFY_SOURCE feature.

Cc: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/brocade/bna/bnad_ethtool.c b/drivers/net/ethernet/brocade/bna/bnad_ethtool.c
index 286593922139e1f59e6c66c33df8a4d54ee33314..31032de5843b158e3a1aca0e742d60d31d1b5669 100644 (file)
--- a/drivers/net/ethernet/brocade/bna/bnad_ethtool.c
+++ b/drivers/net/ethernet/brocade/bna/bnad_ethtool.c
@@ -547,8 +547,8 @@ bnad_get_strings(struct net_device *netdev, u32 stringset, u8 *string)
                for (i = 0; i < BNAD_ETHTOOL_STATS_NUM; i++) {
                        BUG_ON(!(strlen(bnad_net_stats_strings[i]) <
                                   ETH_GSTRING_LEN));
-                       memcpy(string, bnad_net_stats_strings[i],
-                              ETH_GSTRING_LEN);
+                       strncpy(string, bnad_net_stats_strings[i],
+                               ETH_GSTRING_LEN);
                        string += ETH_GSTRING_LEN;
                }
                bmap = bna_tx_rid_mask(&bnad->bna);