bnep_add_connection() needs to keep holding the bnep_session_sem while
reading dev->name (just like bnep_get_connlist() does); otherwise the
bnep_session() thread can concurrently free the net_device, which can for
example be triggered by a concurrent bnep_del_connection().
(This UAF is fairly uninteresting from a security perspective;
calling bnep_add_connection() requires passing a capable(CAP_NET_ADMIN)
check. It also requires completely tearing down a netdev during a fairly
tight race window.)
Cc: stable@vger.kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jann Horn <jannh@google.com>
---
I have tested that this bug can lead to UAF by using KASAN and
introducing an artificial delay with mdelay().
---
net/bluetooth/bnep/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/bluetooth/bnep/core.c b/net/bluetooth/bnep/core.c
index 853c8d7644b5..0de5df690bd0 100644
--- a/net/bluetooth/bnep/core.c
+++ b/net/bluetooth/bnep/core.c
@@ -645,8 +645,8 @@ int bnep_add_connection(struct bnep_connadd_req *req, struct socket *sock)
goto failed;
}
- up_write(&bnep_session_sem);
strcpy(req->device, dev->name);
+ up_write(&bnep_session_sem);
return 0;
failed:
---
base-commit: 1d5dcaa3bd65f2e8c9baa14a393d3a2dc5db7524
change-id: 20260512-bnep-add-uaf-f730caec3b13
--
Jann Horn <jannh@google.com>