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 51626b4175c00957891a62968ff3cdaf4aad7183..3fab6c81917f7285aa9ef871001fef6e1d1768c5 100644 (file)
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -2604,6 +2604,8 @@ 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 33ce0484b2a03f9b31858a06257f176fdf6bb3a7..45cbade9ad68cfdd4ecc198b0abced521d8ed974 100644 (file)
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -95,6 +95,9 @@ 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) {