[PATCH] bna: ethtool: Avoid reading past end of buffer

From	Kees Cook <keescook@chromium.org>
Newsgroups	linux.kernel
Subject	[PATCH] bna: ethtool: Avoid reading past end of buffer
Date	2017-05-06 00:40 +0200
Message-ID	<tDU3f-7VT-17@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

Show all headers | View raw

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>
---
 drivers/net/ethernet/brocade/bna/bnad_ethtool.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/brocade/bna/bnad_ethtool.c b/drivers/net/ethernet/brocade/bna/bnad_ethtool.c
index 286593922139..31032de5843b 100644
--- 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);
-- 
2.7.4


-- 
Kees Cook
Pixel Security

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[PATCH] bna: ethtool: Avoid reading past end of buffer Kees Cook <keescook@chromium.org> - 2017-05-06 00:40 +0200
  Re: [PATCH] bna: ethtool: Avoid reading past end of buffer David Miller <davem@davemloft.net> - 2017-05-08 20:50 +0200

csiph-web