[PATCH 5.14 232/334] Bluetooth: add timeout sanity check to hci_inquiry

Greg Kroah-Hartman
2021-09-13T14:44:03Z

From: Pavel Skripkin <paskripkin@gmail.com>

[ Upstream commit f41a4b2b5eb7872109723dab8ae1603bdd9d9ec1 ]

Syzbot hit "task hung" bug in hci_req_sync(). The problem was in
unreasonable huge inquiry timeout passed from userspace.
Fix it by adding sanity check for timeout value to hci_inquiry().

Since hci_inquiry() is the only user of hci_req_sync() with user
controlled timeout value, it makes sense to check timeout value in
hci_inquiry() and don't touch hci_req_sync().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-and-tested-by: syzbot+be2baed593ea56c6a84c@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/bluetooth/hci_core.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 2331612839d7..4c25bcd1ac4c 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1343,6 +1343,12 @@ int hci_inquiry(void __user *arg)
goto done;
}

+ /* Restrict maximum inquiry length to 60 seconds */
+ if (ir.length > 60) {
+ err = -EINVAL;
+ goto done;
+ }
+
hci_dev_lock(hdev);
if (inquiry_cache_age(hdev) > INQUIRY_CACHE_AGE_MAX ||
inquiry_cache_empty(hdev) || ir.flags & IREQ_CACHE_FLUSH) {
--
2.30.2