[PATCH review for 4.4 04/26] mac80211_hwsim: check HWSIM_ATTR_RADIO_NAME length

From: Levin, Alexander (Sasha Levin)
Date: Sun Sep 24 2017 - 21:21:08 EST


From: Johannes Berg <johannes.berg@xxxxxxxxx>

[ Upstream commit ff4dd73dd2b4806419f8ff65cbce11d5019548d0 ]

Unfortunately, the nla policy was defined to have HWSIM_ATTR_RADIO_NAME
as an NLA_STRING, rather than NLA_NUL_STRING, so we can't use it as a
NUL-terminated string in the kernel.

Rather than break the API, kasprintf() the string to a new buffer to
guarantee NUL termination.

Reported-by: Andrew Zaborowski <andrew.zaborowski@xxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
---
drivers/net/wireless/mac80211_hwsim.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 019d7165a045..2a996a68fc2b 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -2884,6 +2884,7 @@ static int hwsim_register_received_nl(struct sk_buff *skb_2,
static int hwsim_new_radio_nl(struct sk_buff *msg, struct genl_info *info)
{
struct hwsim_new_radio_params param = { 0 };
+ const char *hwname = NULL;

param.reg_strict = info->attrs[HWSIM_ATTR_REG_STRICT_REG];
param.p2p_device = info->attrs[HWSIM_ATTR_SUPPORT_P2P_DEVICE];
@@ -2897,8 +2898,14 @@ static int hwsim_new_radio_nl(struct sk_buff *msg, struct genl_info *info)
if (info->attrs[HWSIM_ATTR_NO_VIF])
param.no_vif = true;

- if (info->attrs[HWSIM_ATTR_RADIO_NAME])
- param.hwname = nla_data(info->attrs[HWSIM_ATTR_RADIO_NAME]);
+ if (info->attrs[HWSIM_ATTR_RADIO_NAME]) {
+ hwname = kasprintf(GFP_KERNEL, "%.*s",
+ nla_len(info->attrs[HWSIM_ATTR_RADIO_NAME]),
+ (char *)nla_data(info->attrs[HWSIM_ATTR_RADIO_NAME]));
+ if (!hwname)
+ return -ENOMEM;
+ param.hwname = hwname;
+ }

if (info->attrs[HWSIM_ATTR_USE_CHANCTX])
param.use_chanctx = true;
@@ -2926,11 +2933,15 @@ static int hwsim_del_radio_nl(struct sk_buff *msg, struct genl_info *info)
s64 idx = -1;
const char *hwname = NULL;

- if (info->attrs[HWSIM_ATTR_RADIO_ID])
+ if (info->attrs[HWSIM_ATTR_RADIO_ID]) {
idx = nla_get_u32(info->attrs[HWSIM_ATTR_RADIO_ID]);
- else if (info->attrs[HWSIM_ATTR_RADIO_NAME])
- hwname = (void *)nla_data(info->attrs[HWSIM_ATTR_RADIO_NAME]);
- else
+ } else if (info->attrs[HWSIM_ATTR_RADIO_NAME]) {
+ hwname = kasprintf(GFP_KERNEL, "%.*s",
+ nla_len(info->attrs[HWSIM_ATTR_RADIO_NAME]),
+ (char *)nla_data(info->attrs[HWSIM_ATTR_RADIO_NAME]));
+ if (!hwname)
+ return -ENOMEM;
+ } else
return -EINVAL;

spin_lock_bh(&hwsim_radio_lock);
@@ -2939,7 +2950,8 @@ static int hwsim_del_radio_nl(struct sk_buff *msg, struct genl_info *info)
if (data->idx != idx)
continue;
} else {
- if (strcmp(hwname, wiphy_name(data->hw->wiphy)))
+ if (!hwname ||
+ strcmp(hwname, wiphy_name(data->hw->wiphy)))
continue;
}

@@ -2947,10 +2959,12 @@ static int hwsim_del_radio_nl(struct sk_buff *msg, struct genl_info *info)
spin_unlock_bh(&hwsim_radio_lock);
mac80211_hwsim_del_radio(data, wiphy_name(data->hw->wiphy),
info);
+ kfree(hwname);
return 0;
}
spin_unlock_bh(&hwsim_radio_lock);

+ kfree(hwname);
return -ENODEV;
}

--
2.11.0