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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id z12-20020a6553cc000000b0041d6d37deb5sm6413190pgr.81.2022.09.23.21.08.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Sep 2022 21:08:37 -0700 (PDT) From: Kees Cook To: Krzysztof Kozlowski Cc: Kees Cook , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, "Gustavo A. R. Silva" , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] NFC: hci: Split memcpy() of struct hcp_message flexible array Date: Fri, 23 Sep 2022 21:08:35 -0700 Message-Id: <20220924040835.3364912-1-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1692; h=from:subject; bh=L3jycFmba5E2CH09pA5cygiCtitH/bmlm+CqI6heXOk=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBjLoLD0YsYw2J2xQ0tZE9KGrEoJ8NYLRlKPkcvzZqz yQEQEbyJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYy6CwwAKCRCJcvTf3G3AJk4LEA ClWkoy6IOy1qfx50hwizKTjj+BKE2WJ46hPcko+MF5I0MZ6Q4ZATjEiGbraCyQGgtwYzk8cLV9p8gQ 8GKPpSW0UJojL6M7Hc3ucQo7yVKecKiBbJnVHX41ZLSARp5binAPgqa5RbCttvbBwbznrihcKb7DTs w/5Wkc0UBwh+yUMHTpvzMGwtamUHlQXDKNIoS26Osa4pBT5M3AD3rsJWcuDEVTSrQOMxBvcJwHkaIY xvXsS00hHt1OK/JRz290YhG0SN/sORY5owHBJAUGwoRo7lwoqcJPWyG/ejOCJLk1wOxXFdAUE2sUMY mTt3ewUROH/wBSuhk3tjZbEVGrzokGmfhiLLoMRZyBvc96zzi34I3JuEU1rOWaC05ufU2FLv7yIwur UrwkV3GHMIxXi0+Yx37Ty5KhZaQydPHbZwLfaJnpaIq3FU0ay2BGVnI1eaPQzewRe/Z6XixsBh5tBs d5Qx3+G46QMvlLNIPsRYn+tuH+6tUuCKPPA6ySkZaSfp3a69YISMghumcZLBFMTh9TPejpmy8/ECWq IgqQ6y0Jq4xC1WE06cgdkiHTJNpAC85uTT8hj+wCOSqtbkjpoSPyUAbHn/DtjyEhXoWsf0QsRdC+t2 rIQSEM25WqhwuUwEipx/MEvW3e8Jhwd/X8f4lmiT5SfwTV4GuVeqO820uA5g== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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. This split already existed for the "firstfrag" case, so just generalize the logic further. [1] https://lore.kernel.org/linux-hardening/20220901065914.1417829-2-keesco= ok@chromium.org/ Cc: Krzysztof Kozlowski Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: netdev@vger.kernel.org Reported-by: "Gustavo A. R. Silva" Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva Reviewed-by: Krzysztof Kozlowski --- net/nfc/hci/hcp.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/net/nfc/hci/hcp.c b/net/nfc/hci/hcp.c index 05c60988f59a..4902f5064098 100644 --- a/net/nfc/hci/hcp.c +++ b/net/nfc/hci/hcp.c @@ -73,14 +73,12 @@ int nfc_hci_hcp_message_tx(struct nfc_hci_dev *hdev, u8= pipe, if (firstfrag) { firstfrag =3D false; packet->message.header =3D HCP_HEADER(type, instruction); - if (ptr) { - memcpy(packet->message.data, ptr, - data_link_len - 1); - ptr +=3D data_link_len - 1; - } } else { - memcpy(&packet->message, ptr, data_link_len); - ptr +=3D data_link_len; + packet->message.header =3D *ptr++; + } + if (ptr) { + memcpy(packet->message.data, ptr, data_link_len - 1); + ptr +=3D data_link_len - 1; } =20 /* This is the last fragment, set the cb bit */ --=20 2.34.1