From: Florian Fainelli <f.fainelli@gmail.com>
Date: Mon, 30 Mar 2020 14:38:46 -0700
Subject: net: dsa: bcm_sf2: Fix overflow checks
Git-commit: d0802dc411f469569a537283b6f3833af47aece9
Patch-mainline: 5.7-rc1
References: git-fixes

Commit f949a12fd697 ("net: dsa: bcm_sf2: fix buffer overflow doing
set_rxnfc") tried to fix the some user controlled buffer overflows in
bcm_sf2_cfp_rule_set() and bcm_sf2_cfp_rule_del() but the fix was using
CFP_NUM_RULES, which while it is correct not to overflow the bitmaps, is
not representative of what the device actually supports. Correct that by
using bcm_sf2_cfp_rule_size() instead.

The latter subtracts the number of rules by 1, so change the checks from
greater than or equal to greater than accordingly.

Fixes: f949a12fd697 ("net: dsa: bcm_sf2: fix buffer overflow doing set_rxnfc")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/net/dsa/bcm_sf2_cfp.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/drivers/net/dsa/bcm_sf2_cfp.c
+++ b/drivers/net/dsa/bcm_sf2_cfp.c
@@ -130,17 +130,14 @@ static int bcm_sf2_cfp_rule_set(struct d
 	    (fs->m_ext.vlan_etype || fs->m_ext.data[1]))
 		return -EINVAL;
 
-	if (fs->location != RX_CLS_LOC_ANY && fs->location >= CFP_NUM_RULES)
+	if (fs->location != RX_CLS_LOC_ANY &&
+	    fs->location > bcm_sf2_cfp_rule_size(priv))
 		return -EINVAL;
 
 	if (fs->location != RX_CLS_LOC_ANY &&
 	    test_bit(fs->location, priv->cfp.used))
 		return -EBUSY;
 
-	if (fs->location != RX_CLS_LOC_ANY &&
-	    fs->location > bcm_sf2_cfp_rule_size(priv))
-		return -EINVAL;
-
 	ip_frag = be32_to_cpu(fs->m_ext.data[0]);
 
 	/* We do not support discarding packets, check that the
@@ -333,7 +330,7 @@ static int bcm_sf2_cfp_rule_del(struct b
 	int ret;
 	u32 reg;
 
-	if (loc >= CFP_NUM_RULES)
+	if (loc > bcm_sf2_cfp_rule_size(priv))
 		return -EINVAL;
 
 	/* Refuse deletion of unused rules, and the default reserved rule */