Commit a7cfebcb authored Apr 03, 2018 by Johannes Berg

cfg80211: limit wiphy names to 128 bytes



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>

parent 911a2648

include/uapi/linux/nl80211.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -2698,6 +2698,8 @@ 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

net/wireless/core.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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) {