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cfg80211: limit wiphy names to 128 bytes

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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>
This commit is contained in:
Johannes Berg 2018-04-03 14:33:49 +02:00
parent 911a26484c
commit a7cfebcb75
2 changed files with 5 additions and 0 deletions
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2
include/uapi/linux/nl80211.h
View File

@ -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

3
net/wireless/core.c
View File

@ -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) {