cfg80211: limit wiphy names to 128 bytes

commit a7cfebcb7594a24609268f91299ab85ba064bf82 upstream.

There's currently no limit on wiphy names, other than netlink
message size and memory limitations, but that causes issues when,
for example, the wiphy name is used in a uevent, e.g. in rfkill
where we use the same name for the rfkill instance, and then the
buffer there is "only" 2k for the environment variables.

This was reported by syzkaller, which used a 4k name.

Limit the name to something reasonable, I randomly picked 128.

Reported-by: syzbot+230d9e642a85d3fec29c@syzkaller.appspotmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 1f0b4cf5dd03df822db7903ccddb3e9021520085..f4227173b5d85c0318a74c806a5a9e228f958955 100644 (file)
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -2195,6 +2195,8 @@ enum nl80211_attrs {
 #define NL80211_ATTR_KEYS NL80211_ATTR_KEYS
 #define NL80211_ATTR_FEATURE_FLAGS NL80211_ATTR_FEATURE_FLAGS
 
+#define NL80211_WIPHY_NAME_MAXLEN              128
+
 #define NL80211_MAX_SUPP_RATES                 32
 #define NL80211_MAX_SUPP_HT_RATES              77
 #define NL80211_MAX_SUPP_REG_RULES             64

diff --git a/net/wireless/core.c b/net/wireless/core.c
index eeaf83acba1b9b92815243247947cfc9a3256b60..a1e909ae0f78159b4b2b1f2a9fa59e5ec8fa6e46 100644 (file)
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -94,6 +94,9 @@ static int cfg80211_dev_check_name(struct cfg80211_registered_device *rdev,
 
        ASSERT_RTNL();
 
+       if (strlen(newname) > NL80211_WIPHY_NAME_MAXLEN)
+               return -EINVAL;
+
        /* prohibit calling the thing phy%d when %d is not its number */
        sscanf(newname, PHY_NAME "%d%n", &wiphy_idx, &taken);
        if (taken == strlen(newname) && wiphy_idx != rdev->wiphy_idx) {