[PATCH] libertas: Avoid reading past end of buffer

Subsystems: marvell libertas wireless driver, the rest

STALE3377d

3 messages, 2 authors, 2017-05-10 · open the first message on its own page

[PATCH] libertas: Avoid reading past end of buffer

From: Kees Cook <hidden>
Date: 2017-05-09 23:23:38 

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.

Cc: Daniel Micay <redacted>
Signed-off-by: Kees Cook <redacted>
---
 drivers/net/wireless/marvell/libertas/mesh.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas/mesh.c b/drivers/net/wireless/marvell/libertas/mesh.c
index d0c881dd5846..d0b1948ca242 100644
--- 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);
 		}
 		break;
 	}
-- 
2.7.4


-- 
Kees Cook
Pixel Security

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

From: Joe Perches <joe@perches.com>
Date: 2017-05-10 04:33:26 

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.
[]
quoted hunk
diff --git a/drivers/net/wireless/marvell/libertas/mesh.c b/drivers/net/wireless/marvell/libertas/mesh.c
[]
quoted hunk
@@ -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,

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

From: Kees Cook <hidden>
Date: 2017-05-10 19:06:07 

On Tue, May 9, 2017 at 9:33 PM, Joe Perches [off-list ref] wrote:
quoted hunk
On Tue, 2017-05-09 at 16:23 -0700, Kees Cook wrote:
quoted
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.
[]
quoted
diff --git a/drivers/net/wireless/marvell/libertas/mesh.c b/drivers/net/wireless/marvell/libertas/mesh.c
[]
quoted
@@ -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,
Ah yeah! And that simplifies the memcpy too, since it can just do it
in one go. New patch on the way...

-Kees

-- 
Kees Cook
Pixel Security
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