[PATCH 6.1 205/451] Bluetooth: fix use-after-free in accessing skb after sending it

Sasha Levin
2024-03-24T23:15:29Z

From: Pauli Virtanen <pav@iki.fi>

[ Upstream commit 947ec0d002dce8577b655793dcc6fc78d67b7cb6 ]

hci_send_cmd_sync first sends skb and then tries to clone it. However,
the driver may have already freed the skb at that point.

Fix by cloning the sent_cmd cloned just above, instead of the original.

Log:
================================================================
BUG: KASAN: slab-use-after-free in __copy_skb_header+0x1a/0x240
...
Call Trace: ..
__skb_clone+0x59/0x2c0
hci_cmd_work+0x3b3/0x3d0 [bluetooth]
process_one_work+0x459/0x900
...
Allocated by task 129: ...
__alloc_skb+0x1ae/0x220
__hci_cmd_sync_sk+0x44c/0x7a0 [bluetooth]
__hci_cmd_sync_status+0x24/0xb0 [bluetooth]
set_cig_params_sync+0x778/0x7d0 [bluetooth]
...
Freed by task 0: ...
kmem_cache_free+0x157/0x3c0
__usb_hcd_giveback_urb+0x11e/0x1e0
usb_giveback_urb_bh+0x1ad/0x2a0
tasklet_action_common.isra.0+0x259/0x4a0
__do_softirq+0x15b/0x5a7
================================================================

Fixes: 2615fd9a7c25 ("Bluetooth: hci_sync: Fix overwriting request callback")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/bluetooth/hci_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 88e9d7e0865a2..70f24dc75b596 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -4176,7 +4176,7 @@ static void hci_send_cmd_sync(struct hci_dev *hdev, struct sk_buff *skb)
if (hci_req_status_pend(hdev) &&
!hci_dev_test_and_set_flag(hdev, HCI_CMD_PENDING)) {
kfree_skb(hdev->req_skb);
- hdev->req_skb = skb_clone(skb, GFP_KERNEL);
+ hdev->req_skb = skb_clone(hdev->sent_cmd, GFP_KERNEL);
}

atomic_dec(&hdev->cmd_cnt);
--
2.43.0