[PATCH 6.1 032/112] Bluetooth: hci_event: shut up a false-positive warning

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6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@xxxxxxxx>

[ Upstream commit a5812c68d849505ea657f653446512b85887f813 ]

Turning on -Wstringop-overflow globally exposed a misleading compiler
warning in bluetooth:

net/bluetooth/hci_event.c: In function 'hci_cc_read_class_of_dev':
net/bluetooth/hci_event.c:524:9: error: 'memcpy' writing 3 bytes into a
region of size 0 overflows the destination [-Werror=stringop-overflow=]
  524 |         memcpy(hdev->dev_class, rp->dev_class, 3);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The problem here is the check for hdev being NULL in bt_dev_dbg() that
leads the compiler to conclude that hdev->dev_class might be an invalid
pointer access.

Add another explicit check for the same condition to make sure gcc sees
this cannot happen.

Fixes: a9de9248064b ("[Bluetooth] Switch from OGF+OCF to using only opcodes")
Fixes: 1b56c90018f0 ("Makefile: Enable -Wstringop-overflow globally")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/bluetooth/hci_event.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index c86a45344fe28..5e406e8716a0e 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -515,6 +515,9 @@ static u8 hci_cc_read_class_of_dev(struct hci_dev *hdev, void *data,
 {
 	struct hci_rp_read_class_of_dev *rp = data;
 
+	if (WARN_ON(!hdev))
+		return HCI_ERROR_UNSPECIFIED;
+
 	bt_dev_dbg(hdev, "status 0x%2.2x", rp->status);
 
 	if (rp->status)
-- 
2.43.0







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