[PATCH] wifi: mac80211: avoid WARN in set_bitrate_mask when sdata not in driver

[PATCH] wifi: mac80211: avoid WARN in set_bitrate_mask when sdata not in driver

[Rik van Riel]

ieee80211_set_bitrate_mask() checks if the interface is running via
ieee80211_sdata_running(), but it does not check if the interface is
still present in the driver.

When sdata is running but IEEE80211_SDATA_IN_DRIVER is not set, the
call reaches drv_set_bitrate_mask() in driver-ops.h which hits

  wlan1: Failed check-sdata-in-driver check, flags: 0x0
  WARNING: net/mac80211/driver-ops.h:884 at drv_set_bitrate_mask

Syzkaller triggers this via wext SIOCSIWRATE ioctl. The Call Trace shows
wext_ioctl_dispatch() in wext-core.c dispatching the ioctl, calling
ioctl_standard_call() for SIOCSIWRATE, which calls cfg80211_wext_siwrate()
in wext-compat.c. That builds a bitrate mask and calls
rdev_set_bitrate_mask() which ends up in ieee80211_set_bitrate_mask() in
cfg.c. The interface is marked running via SDATA_STATE_RUNNING but
flags is 0, so check_sdata_in_driver() fails.

When the interface is being torn down, or when wext ioctl is issued
during interface bringup before drv_add_interface() sets IN_DRIVER, the
running check passes while IN_DRIVER is clear.

Check IEEE80211_SDATA_IN_DRIVER in ieee80211_set_bitrate_mask() before
calling the driver, returning -ENETDOWN. This avoids the WARN_ONCE in
driver-ops.h and matches other cfg.c operations that bail early when not
in driver.

This change should be safe because wiphy mutex is held in
cfg80211_wext_siwrate() via guard(wiphy), and IN_DRIVER is set/cleared
under RTNL and wiphy paths in drv_add_interface() and
drv_remove_interface() in driver-ops.c, so the check is race-free
against driver add/remove. Returning -ENETDOWN is the same error other
not-running paths use and does not introduce new locking.

Reported-by: syzbot+af177aa139efdd13a9da@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=af177aa139efdd13a9da
Link: https://lore.kernel.org/all/6a75205c.59b6c763.2bba34.00c3.GAE@google.com/
Fixes: 554a43d5e77e ("mac80211: check sdata_running on ieee80211_set_bitrate_mask")
Cc: stable@vger.kernel.org
Assisted-by: Hermes:muse-spark-1.2 syzkaller
Signed-off-by: Rik van Riel <riel@surriel.com>
---
 net/mac80211/cfg.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 43f142624d33..b66baa98b98d 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -4113,6 +4113,9 @@ static int ieee80211_set_bitrate_mask(struct wiphy *wiphy,
 	if (!ieee80211_sdata_running(sdata))
 		return -ENETDOWN;
 
+	if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+		return -ENETDOWN;
+
 	/*
 	 * If active validate the setting and reject it if it doesn't leave
 	 * at least one basic rate usable, since we really have to be able
-- 
2.55.0