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SubjectRE: [PATCH] [next] HID: hyperv: Replace one-element array with flexible-array member
On Mon, 17 Oct 2022, Michael Kelley (LINUX) wrote:

> > One-element arrays are deprecated, and we are replacing them with
> > flexible array members instead. So, replace one-element array with
> > flexible-array member in structs synthhid_msg, synthhid_input_report,
> > pipe_prt_msg and refactor the rest of the code accordingly.
> >
> > This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> > routines on memcpy() and help us make progress towards globally
> > enabling -fstrict-flex-arrays=3 [1].
> >
> > Link: https://github.com/KSPP/linux/issues/79
> > Link: https://github.com/KSPP/linux/issues/210
> > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 [1]
> >
> > Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
> > ---
> > drivers/hid/hid-hyperv.c | 17 +++++++----------
> > 1 file changed, 7 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
> > index e0bc73124196..208cf8d981a5 100644
> > --- a/drivers/hid/hid-hyperv.c
> > +++ b/drivers/hid/hid-hyperv.c
> > @@ -61,7 +61,7 @@ struct synthhid_msg_hdr {
> >
> > struct synthhid_msg {
> > struct synthhid_msg_hdr header;
> > - char data[1]; /* Enclosed message */
> > + char data[]; /* Enclosed message */
> > };
> >
> > union synthhid_version {
> > @@ -99,7 +99,7 @@ struct synthhid_device_info_ack {
> >
> > struct synthhid_input_report {
> > struct synthhid_msg_hdr header;
> > - char buffer[1];
> > + char buffer[];
> > };
> >
> > #pragma pack(pop)
> > @@ -118,7 +118,7 @@ enum pipe_prot_msg_type {
> > struct pipe_prt_msg {
> > enum pipe_prot_msg_type type;
> > u32 size;
> > - char data[1];
> > + char data[];
> > };
> >
> > struct mousevsc_prt_msg {
> > @@ -232,7 +232,7 @@ static void mousevsc_on_receive_device_info(struct
> > mousevsc_dev *input_device,
> >
> > ret = vmbus_sendpacket(input_device->device->channel,
> > &ack,
> > - sizeof(struct pipe_prt_msg) - sizeof(unsigned char) +
> > + sizeof(struct pipe_prt_msg) +
> > sizeof(struct synthhid_device_info_ack),
> > (unsigned long)&ack,
> > VM_PKT_DATA_INBAND,
> > @@ -271,16 +271,14 @@ static void mousevsc_on_receive(struct hv_device *device,
> > * malicious/buggy hypervisor/host, add a check here to
> > * ensure we don't corrupt memory.
> > */
> > - if ((pipe_msg->size + sizeof(struct pipe_prt_msg)
> > - - sizeof(unsigned char))
> > + if (struct_size(pipe_msg, data, pipe_msg->size)
> > > sizeof(struct mousevsc_prt_msg)) {
> > WARN_ON(1);
> > break;
> > }
> >
> > memcpy(&input_dev->protocol_resp, pipe_msg,
> > - pipe_msg->size + sizeof(struct pipe_prt_msg) -
> > - sizeof(unsigned char));
> > + struct_size(pipe_msg, data, pipe_msg->size));
> > complete(&input_dev->wait_event);
> > break;
> >
> > @@ -359,8 +357,7 @@ static int mousevsc_connect_to_vsp(struct hv_device *device)
> > request->request.version_requested.version = SYNTHHID_INPUT_VERSION;
> >
> > ret = vmbus_sendpacket(device->channel, request,
> > - sizeof(struct pipe_prt_msg) -
> > - sizeof(unsigned char) +
> > + sizeof(struct pipe_prt_msg) +
> > sizeof(struct synthhid_protocol_request),
> > (unsigned long)request,
> > VM_PKT_DATA_INBAND,
> > --
> > 2.37.3
>
> Reviewed-by: Michael Kelley <mikelley@microsoft.com>

Thanks, applied.

--
Jiri Kosina
SUSE Labs

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