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Subject[34-longterm 209/209] niu: Fix kernel buffer overflow for ETHTOOL_GRXCLSRLALL
Date
From: Ben Hutchings <bhutchings@solarflare.com>

=====================================================================
| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|
=====================================================================

commit ee9c5cfad29c8a13199962614b9b16f1c4137ac9 upstream.

niu_get_ethtool_tcam_all() assumes that its output buffer is the right
size, and warns before returning if it is not. However, the output
buffer size is under user control and ETHTOOL_GRXCLSRLALL is an
unprivileged ethtool command. Therefore this is at least a local
denial-of-service vulnerability.

Change it to check before writing each entry and to return an error if
the buffer is already full.

Compile-tested only.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
drivers/net/niu.c | 16 ++++++----------
1 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/net/niu.c b/drivers/net/niu.c
index d5cd16b..408d10f 100644
--- a/drivers/net/niu.c
+++ b/drivers/net/niu.c
@@ -7263,32 +7263,28 @@ static int niu_get_ethtool_tcam_all(struct niu *np,
struct niu_parent *parent = np->parent;
struct niu_tcam_entry *tp;
int i, idx, cnt;
- u16 n_entries;
unsigned long flags;
-
+ int ret = 0;

/* put the tcam size here */
nfc->data = tcam_get_size(np);

niu_lock_parent(np, flags);
- n_entries = nfc->rule_cnt;
for (cnt = 0, i = 0; i < nfc->data; i++) {
idx = tcam_get_index(np, i);
tp = &parent->tcam[idx];
if (!tp->valid)
continue;
+ if (cnt == nfc->rule_cnt) {
+ ret = -EMSGSIZE;
+ break;
+ }
rule_locs[cnt] = i;
cnt++;
}
niu_unlock_parent(np, flags);

- if (n_entries != cnt) {
- /* print warning, this should not happen */
- netdev_info(np->dev, "niu%d: In %s(): n_entries[%d] != cnt[%d]!!!\n",
- np->parent->index, __func__, n_entries, cnt);
- }
-
- return 0;
+ return ret;
}

static int niu_get_nfc(struct net_device *dev, struct ethtool_rxnfc *cmd,
--
1.7.4.4


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