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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id t23-20020a17090ae51700b00226d4009505sm278581pjy.3.2023.01.05.22.17.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Jan 2023 22:17:05 -0800 (PST) From: Kees Cook To: Laurent Pinchart Cc: Kees Cook , ionut_n2001@yahoo.com, Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] media: uvcvideo: Silence memcpy() run-time false positive warnings Date: Thu, 5 Jan 2023 22:17:04 -0800 Message-Id: <20230106061659.never.817-kees@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2208; h=from:subject:message-id; bh=HRw9p7KL+4QYDBK7zvJtazO5keiEwenv1mXQer7Jbt4=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBjt7zf29HyDZw/F4MlHzU+Bl4G8jxpLHfoOnTvU5u5 FlEqB3GJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCY7e83wAKCRCJcvTf3G3AJm9kD/ 47yg+LzAvpwtJYOb3OyV+MyCV2HpjQshWvE4+pgbpPOInmvvsqXeKW0Wm8McFGBzx2yl6blx5Pwpca /47EBMRpOiaT3GJNNxENwSAQHww/dF0ks2rY0PhvtPJbR+ZGd0MsSL03PBC85Kic9R1sf0fibXcTse 1/1izkyXUaxNymvLqFlfEIzecRP8k/7OXqvn9QcyXT/SOtVQb40dPRMPuxukLzjWqFxL0dA+kTz2uc RNSPIVy75p4LrE/mJBnwHLx/1tB3SJqNOxdimbYNR7+YP/fpUq6Bh7o1mhZJID8BxJJNDvbRqTPsn9 uURfsmbYsTr7rdQtiXrc2MLqikfo69Xdwm5Ufx/hpJ16yjjaU1d4ft7iT1kjKRc0hIsLsZVJgOXKhW hKw0Mrd5QMh7dm0xeoH49RHCtw3HUPdFfH+OdzuwPnVoPBSUDZuvKvdZ+Z/vpKbtOVIl/n0gzG/97j 8o76yXgd56XlarYhCNPv1gMoPKB1G8/7NUdoBNRR2QbCYZpCWjKuzxzfQ+sdKw4VZ3qTCLa1zS3TLV A49o0bouLm+QU+00+amCZ0rjTUw4yIyFfOm31Sg3Shec09zsbbMGjf9ShNfNpzy0zxZEswGJzvcZTh w4R++sq98XmsmnzSX/87MTHp2cWhQxB276FXEZS0Unn1URmr+UqjmtV/wfkg== 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" The memcpy() in uvc_video_decode_meta() intentionally copies across the length and flags members and into the trailing buf flexible array. Split the copy so that the compiler can better reason about (the lack of) buffer overflows here. Avoid the run-time false positive warning: memcpy: detected field-spanning write (size 12) of single field "&meta->l= ength" at drivers/media/usb/uvc/uvc_video.c:1355 (size 1) Additionally fix a typo in the documentation for struct uvc_meta_buf. Reported-by: ionut_n2001@yahoo.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D216810 Cc: Laurent Pinchart Cc: Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org Signed-off-by: Kees Cook Reviewed-by: Laurent Pinchart --- drivers/media/usb/uvc/uvc_video.c | 4 +++- include/uapi/linux/uvcvideo.h | 2 +- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_= video.c index d2eb9066e4dc..b67347ab4181 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -1352,7 +1352,9 @@ static void uvc_video_decode_meta(struct uvc_streamin= g *stream, if (has_scr) memcpy(stream->clock.last_scr, scr, 6); =20 - memcpy(&meta->length, mem, length); + meta->length =3D mem[0]; + meta->flags =3D mem[1]; + memcpy(meta->buf, &mem[2], length - 2); meta_buf->bytesused +=3D length + sizeof(meta->ns) + sizeof(meta->sof); =20 uvc_dbg(stream->dev, FRAME, diff --git a/include/uapi/linux/uvcvideo.h b/include/uapi/linux/uvcvideo.h index 8288137387c0..a9d0a64007ba 100644 --- a/include/uapi/linux/uvcvideo.h +++ b/include/uapi/linux/uvcvideo.h @@ -86,7 +86,7 @@ struct uvc_xu_control_query { * struct. The first two fields are added by the driver, they can be used = for * clock synchronisation. The rest is an exact copy of a UVC payload heade= r. * Only complete objects with complete buffers are included. Therefore it's - * always sizeof(meta->ts) + sizeof(meta->sof) + meta->length bytes large. + * always sizeof(meta->ns) + sizeof(meta->sof) + meta->length bytes large. */ struct uvc_meta_buf { __u64 ns; --=20 2.34.1