linux-kernel - [PATCH v3] Bluetooth: hci: fix null-ptr-deref in hci_read_supported

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Message-ID: <20241029194505.2094645-2-iam@sung-woo.kim>
Date: Tue, 29 Oct 2024 19:44:41 +0000
From: Sungwoo Kim <iam@...g-woo.kim>
To: luiz.dentz@...il.com
Cc: daveti@...due.edu,
	benquike@...il.com,
	Sungwoo Kim <iam@...g-woo.kim>,
	Marcel Holtmann <marcel@...tmann.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	linux-bluetooth@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3] Bluetooth: hci: fix null-ptr-deref in hci_read_supported_codecs

Fix __hci_cmd_sync_sk() to return not NULL for unknown opcodes.

__hci_cmd_sync_sk() returns NULL if a command returns a status event.
However, it also returns NULL where an opcode doesn't exist in the
hci_cc table because hci_cmd_complete_evt() assumes status = skb->data[0]
for unknown opcodes.
This leads to null-ptr-deref in cmd_sync for HCI_OP_READ_LOCAL_CODECS as
there is no hci_cc for HCI_OP_READ_LOCAL_CODECS, which always assumes
status = skb->data[0].

KASAN: null-ptr-deref in range [0x0000000000000070-0x0000000000000077]
CPU: 1 PID: 2000 Comm: kworker/u9:5 Not tainted 6.9.0-ga6bcb805883c-dirty #10
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Workqueue: hci7 hci_power_on
RIP: 0010:hci_read_supported_codecs+0xb9/0x870 net/bluetooth/hci_codec.c:138
Code: 08 48 89 ef e8 b8 c1 8f fd 48 8b 75 00 e9 96 00 00 00 49 89 c6 48 ba 00 00 00 00 00 fc ff df 4c 8d 60 70 4c 89 e3 48 c1 eb 03 <0f> b6 04 13 84 c0 0f 85 82 06 00 00 41 83 3c 24 02 77 0a e8 bf 78
RSP: 0018:ffff888120bafac8 EFLAGS: 00010212
RAX: 0000000000000000 RBX: 000000000000000e RCX: ffff8881173f0040
RDX: dffffc0000000000 RSI: ffffffffa58496c0 RDI: ffff88810b9ad1e4
RBP: ffff88810b9ac000 R08: ffffffffa77882a7 R09: 1ffffffff4ef1054
R10: dffffc0000000000 R11: fffffbfff4ef1055 R12: 0000000000000070
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88810b9ac000
FS:  0000000000000000(0000) GS:ffff8881f6c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6ddaa3439e CR3: 0000000139764003 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
 <TASK>
 hci_read_local_codecs_sync net/bluetooth/hci_sync.c:4546 [inline]
 hci_init_stage_sync net/bluetooth/hci_sync.c:3441 [inline]
 hci_init4_sync net/bluetooth/hci_sync.c:4706 [inline]
 hci_init_sync net/bluetooth/hci_sync.c:4742 [inline]
 hci_dev_init_sync net/bluetooth/hci_sync.c:4912 [inline]
 hci_dev_open_sync+0x19a9/0x2d30 net/bluetooth/hci_sync.c:4994
 hci_dev_do_open net/bluetooth/hci_core.c:483 [inline]
 hci_power_on+0x11e/0x560 net/bluetooth/hci_core.c:1015
 process_one_work kernel/workqueue.c:3267 [inline]
 process_scheduled_works+0x8ef/0x14f0 kernel/workqueue.c:3348
 worker_thread+0x91f/0xe50 kernel/workqueue.c:3429
 kthread+0x2cb/0x360 kernel/kthread.c:388
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Fixes: abfeea476c68 ("Bluetooth: hci_sync: Convert MGMT_OP_START_DISCOVERY")

Signed-off-by: Sungwoo Kim <iam@...g-woo.kim>
---
v1 -> v2: make __hci_cmd_sync_sk() not return NULL
v2 -> v3: elaborate reasoning

 net/bluetooth/hci_sync.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 9482bd562..c86f4e42e 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -206,6 +206,12 @@ struct sk_buff *__hci_cmd_sync_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
 		return ERR_PTR(err);
 	}
 
+	/* If command return a status event skb will be set to NULL as there are
+	 * no parameters.
+	 */
+	if (!skb)
+		return ERR_PTR(-ENODATA);
+
 	return skb;
 }
 EXPORT_SYMBOL(__hci_cmd_sync_sk);
@@ -255,6 +261,11 @@ int __hci_cmd_sync_status_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
 	u8 status;
 
 	skb = __hci_cmd_sync_sk(hdev, opcode, plen, param, event, timeout, sk);
+
+	/* If command return a status event, skb will be set to -ENODATA */
+	if (skb == ERR_PTR(-ENODATA))
+		return 0;
+
 	if (IS_ERR(skb)) {
 		if (!event)
 			bt_dev_err(hdev, "Opcode 0x%4.4x failed: %ld", opcode,
@@ -262,13 +273,6 @@ int __hci_cmd_sync_status_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
 		return PTR_ERR(skb);
 	}
 
-	/* If command return a status event skb will be set to NULL as there are
-	 * no parameters, in case of failure IS_ERR(skb) would have be set to
-	 * the actual error would be found with PTR_ERR(skb).
-	 */
-	if (!skb)
-		return 0;
-
 	status = skb->data[0];
 
 	kfree_skb(skb);
-- 
2.43.0