[PATCH 6.18 160/212] wifi: mac80211: fix NULL deref in mesh_matches_local()

Greg Kroah-Hartman
2026-03-23T14:08:50Z

From: Xiang Mei <xmei5@asu.edu>

[ Upstream commit c73bb9a2d33bf81f6eecaa0f474b6c6dbe9855bd ]

mesh_matches_local() unconditionally dereferences ie->mesh_config to
compare mesh configuration parameters. When called from
mesh_rx_csa_frame(), the parsed action-frame elements may not contain a
Mesh Configuration IE, leaving ie->mesh_config NULL and triggering a
kernel NULL pointer dereference.

The other two callers are already safe:
- ieee80211_mesh_rx_bcn_presp() checks !elems->mesh_config before
calling mesh_matches_local()
- mesh_plink_get_event() is only reached through
mesh_process_plink_frame(), which checks !elems->mesh_config, too

mesh_rx_csa_frame() is the only caller that passes raw parsed elements
to mesh_matches_local() without guarding mesh_config. An adjacent
attacker can exploit this by sending a crafted CSA action frame that
includes a valid Mesh ID IE but omits the Mesh Configuration IE,
crashing the kernel.

The captured crash log:

Oops: general protection fault, probably for non-canonical address ...
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
Workqueue: events_unbound cfg80211_wiphy_work
[...]
Call Trace:
<TASK>
? __pfx_mesh_matches_local (net/mac80211/mesh.c:65)
ieee80211_mesh_rx_queued_mgmt (net/mac80211/mesh.c:1686)
[...]
ieee80211_iface_work (net/mac80211/iface.c:1754 net/mac80211/iface.c:1802)
[...]
cfg80211_wiphy_work (net/wireless/core.c:426)
process_one_work (net/kernel/workqueue.c:3280)
? assign_work (net/kernel/workqueue.c:1219)
worker_thread (net/kernel/workqueue.c:3352)
? __pfx_worker_thread (net/kernel/workqueue.c:3385)
kthread (net/kernel/kthread.c:436)
[...]
ret_from_fork_asm (net/arch/x86/entry/entry_64.S:255)
</TASK>

This patch adds a NULL check for ie->mesh_config at the top of
mesh_matches_local() to return false early when the Mesh Configuration
IE is absent.

Fixes: 2e3c8736820b ("mac80211: support functions for mesh")
Reported-by: Weiming Shi <bestswngs@gmail.com>
Signed-off-by: Xiang Mei <xmei5@asu.edu>
Link: https://patch.msgid.link/20260318034244.2595020-1-xmei5@asu.edu
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/mac80211/mesh.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index e235ab7a5651c..4b0eebd5c7cf8 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -79,6 +79,9 @@ bool mesh_matches_local(struct ieee80211_sub_if_data *sdata,
* - MDA enabled
* - Power management control on fc
*/
+ if (!ie->mesh_config)
+ return false;
+
if (!(ifmsh->mesh_id_len == ie->mesh_id_len &&
memcmp(ifmsh->mesh_id, ie->mesh_id, ie->mesh_id_len) == 0 &&
(ifmsh->mesh_pp_id == ie->mesh_config->meshconf_psel) &&
--
2.51.0