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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id p30sm4389467pfh.116.2021.08.17.21.39.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Aug 2021 21:39:13 -0700 (PDT) From: Kees Cook To: Marcel Holtmann Cc: Kees Cook , Johan Hedberg , Luiz Augusto von Dentz , "David S. Miller" , Jakub Kicinski , linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] Bluetooth: mgmt: Pessimize compile-time bounds-check Date: Tue, 17 Aug 2021 21:39:12 -0700 Message-Id: <20210818043912.1466447-1-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1435; h=from:subject; bh=E0l6g+Q1UhnSMK4lDN7R/eQd0SuD7Heg/eD8YzK5Lic=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBhHI7vo8PzMk5HF85TGPbfFBW7iT4mrKvH5KZU5yn/ EkWlbBmJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYRyO7wAKCRCJcvTf3G3AJny4D/ 9kWDf6kh3N+iOlTVivvviWpmxld7NQMSysukicQNgR4Dx8+v5gkpBVF24L+b/IjWlz1Q0bYoNeHz8Q 05okcO2+H3Z2d0C9lqy4dUvYk4v+lNQOuT1oQoc00+Ki7iMO5hIEEw0NcNALnAwNaWAZQyL316p1K0 BwBuVRms/OPZmrNjA7tNB4kTQYn8NKMEw4XmXd3bZGyPtOXHFdznKXPCHKLc7xfp9S5CWWMi74+3S7 XSRxLGCJJNwdqiSP5chMEwUzGdyMkLDloeWyknX4Qk3Mr28EyZXXkrILdpTlAPPCQ2194vXCy7tOEF b54oNbJI8g7HPCqh4oJsLC0R+OMbE/VEr/cobvPT9w6h53xo14s9rTsB7A9ppZr0xZDScpGNK/fj/H qbDej5cRTSDwG9VztYg6h+XLk3u9Sk/H23r0ASa5yszCJLho3tJLICpJhqUJXGxuH6pj17xAFZuh/S DqBArkMNxHyt2q2UmoqpGTR5Fpg4MeOxbzCNo087bCvFkXOembW+nbP7i51jiBaJf3dvtTIc7dl1df pn7CQGa5gcz+dUNskx58QRhJiyGNWpD+8BCP6Co/56dunORoba5Gnpso3ZQCi6Hf3iw/KgNd9/Ob60 YaURx0KP4qAqdhiOzeTVYgPZq+mM6wIV2p0zK/EVOB6DyUOr/U52eyoQBAiQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org 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 Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Cc: "David S. Miller" Cc: Jakub Kicinski Cc: linux-bluetooth@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Kees Cook --- 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,