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Message-Id: <20210818043912.1466447-1-keescook@chromium.org>
Date: Tue, 17 Aug 2021 21:39:12 -0700
From: Kees Cook <keescook@...omium.org>
To: Marcel Holtmann <marcel@...tmann.org>
Cc: Kees Cook <keescook@...omium.org>,
Johan Hedberg <johan.hedberg@...il.com>,
Luiz Augusto von Dentz <luiz.dentz@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH] Bluetooth: mgmt: Pessimize compile-time bounds-check
After gaining __alloc_size hints, GCC thinks it can reach a memcpy()
with eir_len == 0 (since it can't see into the rewrite of status).
Instead, check eir_len == 0, avoiding this future warning:
In function 'eir_append_data',
inlined from 'read_local_oob_ext_data_complete' at net/bluetooth/mgmt.c:7210:12:
./include/linux/fortify-string.h:54:29: warning: '__builtin_memcpy' offset 5 is out of the bounds [0, 3] [-Warray-bounds]
...
net/bluetooth/hci_request.h:133:2: note: in expansion of macro 'memcpy'
133 | memcpy(&eir[eir_len], data, data_len);
| ^~~~~~
Cc: Marcel Holtmann <marcel@...tmann.org>
Cc: Johan Hedberg <johan.hedberg@...il.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: linux-bluetooth@...r.kernel.org
Cc: netdev@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
net/bluetooth/mgmt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 1e21e014efd2..cea01e275f1e 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -7204,7 +7204,7 @@ static void read_local_oob_ext_data_complete(struct hci_dev *hdev, u8 status,
if (!mgmt_rp)
goto done;
- if (status)
+ if (eir_len == 0)
goto send_rsp;
eir_len = eir_append_data(mgmt_rp->eir, 0, EIR_CLASS_OF_DEV,
--
2.30.2
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