net: dsa: bcm_sf2: fix buffer overflow doing set_rxnfc [Linux 5.1]

net: dsa: bcm_sf2: fix buffer overflow doing set_rxnfc [Linux 5.1]

This Linux kernel change "net: dsa: bcm_sf2: fix buffer overflow doing set_rxnfc" is included in the Linux 5.1 release. This change is authored by Dan Carpenter <dan.carpenter [at] oracle.com> on Tue Apr 30 13:44:19 2019 +0300. The commit for this change in Linux stable tree is f949a12 (patch).

net: dsa: bcm_sf2: fix buffer overflow doing set_rxnfc

The "fs->location" is a u32 that comes from the user in ethtool_set_rxnfc().
We can't pass unclamped values to test_bit() or it results in an out of
bounds access beyond the end of the bitmap.

Fixes: 7318166cacad ("net: dsa: bcm_sf2: Add support for ethtool::rxnfc")
Signed-off-by: Dan Carpenter <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

There are 6 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/net/dsa/bcm_sf2_cfp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/dsa/bcm_sf2_cfp.c b/drivers/net/dsa/bcm_sf2_cfp.c
index e6234d2..4212bc4 100644
--- a/drivers/net/dsa/bcm_sf2_cfp.c
+++ b/drivers/net/dsa/bcm_sf2_cfp.c
@@ -886,6 +886,9 @@ static int bcm_sf2_cfp_rule_set(struct dsa_switch *ds, int port,
         fs->m_ext.data[1]))
        return -EINVAL;

+   if (fs->location != RX_CLS_LOC_ANY && fs->location >= CFP_NUM_RULES)
+       return -EINVAL;
+
    if (fs->location != RX_CLS_LOC_ANY &&
        test_bit(fs->location, priv->cfp.used))
        return -EBUSY;
@@ -974,6 +977,9 @@ static int bcm_sf2_cfp_rule_del(struct bcm_sf2_priv *priv, int port, u32 loc)
    struct cfp_rule *rule;
    int ret;

+   if (loc >= CFP_NUM_RULES)
+       return -EINVAL;
+
    /* Refuse deleting unused rules, and those that are not unique since
     * that could leave IPv6 rules with one of the chained rule in the
     * table.

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