From: Du Cheng <ducheng2@gmail.com>
To: Thomas Pedersen <thomas@adapt-ip.com>,
Johannes Berg <johannes@sipsolutions.net>
Cc: linux-wireless@vger.kernel.org,
Shuah Khan <skhan@linuxfoundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Du Cheng <ducheng2@gmail.com>,
syzbot+405843667e93b9790fc1@syzkaller.appspotmail.com
Subject: [PATCH] net: mac80211: fix hard-coding of length check on skb->len in ieee80211_scan_rx()
Date: Mon, 10 May 2021 12:16:49 +0800 [thread overview]
Message-ID: <20210510041649.589754-1-ducheng2@gmail.com> (raw)
Replace hard-coding with compile-time constants for header length
check on skb->len. This skb->len will be checked again further down the
callstack in cfg80211_inform_bss_frame_data() in net/wireless/scan.c
(which has a proper length check with WARN_ON()). If the kernel is
configure to panic_on_warn(), the insuffient check of skb->len in
ieee80211_scan_rx() causes kernel crash in
cfg80211_inform_bss_frame_data().
Bug reported by syzbot:
https://syzkaller.appspot.com/bug?id=183869c2f25b1c8692e381d8fcd69771a99221cc
Reported-by: syzbot+405843667e93b9790fc1@syzkaller.appspotmail.com
Signed-off-by: Du Cheng <ducheng2@gmail.com>
---
This patch has passed syzbot testing.
net/mac80211/scan.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index d4cc9ac2d703..562eda13e802 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -251,13 +251,21 @@ void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
struct ieee80211_mgmt *mgmt = (void *)skb->data;
struct ieee80211_bss *bss;
struct ieee80211_channel *channel;
+ size_t min_hdr_len = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
+
+ if (!ieee80211_is_probe_resp(mgmt->frame_control) &&
+ !ieee80211_is_beacon(mgmt->frame_control) &&
+ !ieee80211_is_s1g_beacon(mgmt->frame_control))
+ return;
if (ieee80211_is_s1g_beacon(mgmt->frame_control)) {
- if (skb->len < 15)
- return;
- } else if (skb->len < 24 ||
- (!ieee80211_is_probe_resp(mgmt->frame_control) &&
- !ieee80211_is_beacon(mgmt->frame_control)))
+ if (ieee80211_is_s1g_short_beacon(mgmt->frame_control))
+ min_hdr_len = offsetof(struct ieee80211_ext, u.s1g_short_beacon.variable);
+ else
+ min_hdr_len = offsetof(struct ieee80211_ext, u.s1g_beacon);
+ }
+
+ if (skb->len < min_hdr_len)
return;
sdata1 = rcu_dereference(local->scan_sdata);
--
2.30.2
next reply other threads:[~2021-05-10 4:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 4:16 Du Cheng [this message]
2021-05-11 22:29 ` [PATCH] net: mac80211: fix hard-coding of length check on skb->len in ieee80211_scan_rx() Shuah Khan
2021-05-12 0:55 ` Du Cheng
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