From: Ayushman Rout <ayushmanrout27@gmail.com>
To: johannes@sipsolutions.net
Cc: nbd@nbd.name, linux-wireless@vger.kernel.org,
linux-kernel@vger.kernel.org,
syzbot+f1ba58d6b55abd13239e@syzkaller.appspotmail.com,
Ayushman Rout <ayushmanrout27@gmail.com>
Subject: [PATCH v2] wifi: mac80211: guard drv_net_setup_tc() against unbound AP_VLAN sdata
Date: Sun, 30 Aug 2026 15:20:28 +0530 [thread overview]
Message-ID: <20260830095028.6397-1-ayushmanrout27@gmail.com> (raw)
syzbot reports a NULL/invalid pointer dereference in
trace_event_raw_event_drv_net_setup_tc(), reached via
ieee80211_netdev_setup_tc() -> drv_net_setup_tc().
drv_net_setup_tc() calls get_bss_sdata(sdata) unconditionally. For an
NL80211_IFTYPE_AP_VLAN interface this does
container_of(sdata->bss, ...), but sdata->bss is only linked
opportunistically at interface-add time when a matching same-address
AP interface exists - it is not enforced, so an AP_VLAN interface can
be fully created and registered with sdata->bss left NULL.
container_of() on NULL yields a small invalid pointer rather than
NULL, which the trace_drv_net_setup_tc tracepoint then dereferences
to read the interface name.
Guard against an unbound AP_VLAN sdata before calling
get_bss_sdata(), matching the WARN_ON_ONCE(!bss) precondition already
used for this same relationship in sta_info.c.
The underlying gap in ieee80211_if_add() - AP_VLAN creation not
requiring a bound bss - is not fixed here; other get_bss_sdata()
callers may share the exposure.
Fixes: 61587f1556fe ("wifi: mac80211: add support for letting drivers register tc offload support")
Reported-by: syzbot+f1ba58d6b55abd13239e@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f1ba58d6b55abd13239e
Signed-off-by: Ayushman Rout <ayushmanrout27@gmail.com>
---
v2: drop the check_sdata_in_driver() call from v1 - syzbot ci flagged
it as reachable via ordinary tc qdisc creation, not a real bug.
https://ci.syzbot.org/series/db0f7870-cfa6-4a9b-b78b-225ce86c2a89
net/mac80211/driver-ops.h | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index f1c0b87fddd5..29743e19a61d 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -1702,6 +1702,15 @@ static inline int drv_net_setup_tc(struct ieee80211_local *local,
might_sleep();
+ /*
+ * AP_VLAN interfaces are only linked to a bss opportunistically at
+ * creation; an unbound one has sdata->bss == NULL, and
+ * get_bss_sdata()'s container_of() on that yields a bogus pointer
+ * rather than NULL, which the tracepoint below then dereferences.
+ */
+ if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN && !sdata->bss)
+ return -EIO;
+
sdata = get_bss_sdata(sdata);
trace_drv_net_setup_tc(local, sdata, type);
if (local->ops->net_setup_tc)
--
2.54.0
reply other threads:[~2026-08-30 9:53 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260830095028.6397-1-ayushmanrout27@gmail.com \
--to=ayushmanrout27@gmail.com \
--cc=johannes@sipsolutions.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-wireless@vger.kernel.org \
--cc=nbd@nbd.name \
--cc=syzbot+f1ba58d6b55abd13239e@syzkaller.appspotmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox