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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id k129-20020a628487000000b0053e5daf1a25sm139467pfd.45.2022.09.26.17.39.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Sep 2022 17:39:29 -0700 (PDT) From: Kees Cook To: Evgeniy Polyakov Cc: Kees Cook , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] w1: Split memcpy() of struct cn_msg flexible array Date: Mon, 26 Sep 2022 17:39:27 -0700 Message-Id: <20220927003927.1942170-1-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1188; h=from:subject; bh=S5QP3TPQ007bwTwLGs3iHsjr0YjJtqD/x5tIisFrd8k=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBjMkY+50POBINt2mFF6tH8OhzUmiluofkXebM++j5G Vgtu0j2JAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYzJGPgAKCRCJcvTf3G3AJquWEA CNazGUUbkJni6TliGwbV4IEgK1WC1RFd1apveljb1lfn3tDGpufcLn4Q9V94nilYf8GeNi3qbg95/y S9lwOAF74Jg1+34s7K/Wzz5/J07EQtndDPEoMZ+JUxt8MoG9E9JW+0rEJmBJ8jLPNQPkqklgo+8ep1 8QETDirCbP1PNhcqS2nHr9dO4JJRaNJcP4RnId/TTdb88i4foxxu0p0kQRX8IB8EvzL777eoMA70gR omlaTJJOKJS5+ZUnM4mOoZPbXbhGT9pewc038LA7092mIGTip9LhWY9FxUlAuMMPu4R6bp9tKrHPPm lEqgKo76aSqOre1c/TiyXRSMgd27XjoyEjN5AUWQm1iKyg0tTo2rCH1VEqK9+F0Ns0qEW3bXAN0AMH rqoFVZ8kKp6Ebo08CfC5P6LlQjJxdi4Ix3qE0ZHOg1MQvE7RjvdMLVoN8iI29hvfBsPKsdyza1MdZz e9Hgy7rJg9PF8VjT2SxDRPvp6cORUf8lBUMPigf4ejrKb5mOjNdZImir0WpQFBXgGxmhtWLuG1E9VI 8uV2GvFBvRymlgoJczQ5e+fAjaAS3diFMnnH9tNm4yrdJZTXTEtZjyGqT8QdhYVJw6+SRhDvL/c1Wm DbmfhGedHB35z+BhSKXKf10xmRJAsJjCxnmYuHm8X9xP0IIvjyIPfgbUIhrQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org To work around a misbehavior of the compiler's ability to see into composite flexible array structs (as detailed in the coming memcpy() hardening series[1]), split the memcpy() of the header and the payload so no false positive run-time overflow warning will be generated. [1] https://lore.kernel.org/linux-hardening/20220901065914.1417829-2-keescook@chromium.org/ Cc: Evgeniy Polyakov Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva --- drivers/w1/w1_netlink.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/w1/w1_netlink.c b/drivers/w1/w1_netlink.c index fa490aa4407c..db110cc442b1 100644 --- a/drivers/w1/w1_netlink.c +++ b/drivers/w1/w1_netlink.c @@ -611,7 +611,8 @@ static void w1_cn_callback(struct cn_msg *cn, struct netlink_skb_parms *nsp) } atomic_set(&block->refcnt, 1); block->portid = nsp->portid; - memcpy(&block->request_cn, cn, sizeof(*cn) + cn->len); + block->request_cn = *cn; + memcpy(block->request_cn.data, cn->data, cn->len); node = (struct w1_cb_node *)(block->request_cn.data + cn->len); /* Sneeky, when not bundling, reply_size is the allocated space