Hi Klaus,
On Tue, 2023-09-05 at 10:38 +0200, Klaus Jensen wrote:
> >
> > +static void nmi_handle_mi_config_get(NMIDevice *nmi, NMIRequest
> > *request)
> > +{
> > + uint32_t dw0 = le32_to_cpu(request->dw0);
> > + uint8_t identifier = FIELD_EX32(dw0,
> > NMI_CMD_CONFIGURATION_GET_DW0,
> > + IDENTIFIER);
> > + const uint8_t *buf;
> > +
> > + static const uint8_t smbus_freq[4] = {
> > + 0x00, /* success */
> > + 0x01, 0x00, 0x00, /* 100 kHz */
> > + };
> > +
> > + static const uint8_t mtu[4] = {
> > + 0x00, /* success */
> > + 0x40, 0x00, /* 64 */
> > + 0x00, /* reserved */
> > + };
> > +
> > + trace_nmi_handle_mi_config_get(identifier);
> > +
> > + switch (identifier) {
> > + case NMI_CMD_CONFIGURATION_GET_SMBUS_FREQ:
> > + buf = smbus_freq;
> > + break;
> > +
> > + case NMI_CMD_CONFIGURATION_GET_MCTP_TRANSMISSION_UNIT:
> > + buf = mtu;
> > + break;
> > +
> > + default:
> > + nmi_set_parameter_error(nmi, 0x0, offsetof(NMIRequest,
> > dw0));
> > + return;
> > + }
> > +
> > + nmi_scratch_append(nmi, buf, sizeof(buf));
> > +}
When I tried to build this patch I got:
```
In file included from /usr/include/string.h:535,
from /home/andrew/src/qemu.org/qemu/include/qemu/osdep.h:112,
from ../hw/nvme/nmi-i2c.c:12:
In function ‘memcpy’,
inlined from ‘nmi_scratch_append’ at ../hw/nvme/nmi-i2c.c:80:5,
inlined from ‘nmi_handle_mi_config_get’ at ../hw/nvme/nmi-i2c.c:246:5,
inlined from ‘nmi_handle_mi’ at ../hw/nvme/nmi-i2c.c:266:9,
inlined from ‘nmi_handle’ at ../hw/nvme/nmi-i2c.c:313:9:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:29:10: error:
‘__builtin_memcpy’ forming offset [4, 7] is out of the bounds [0, 4]
[-Werror=array-bounds=]
29 | return __builtin___memcpy_chk (__dest, __src, __len,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
30 | __glibc_objsize0 (__dest));
| ~~~~~~~~~~~~~~~~~~~~~~~~~~
```
It wasn't clear initially from the error that the source of the problem
was the size associated with the source buffer, especially as there is
some pointer arithmetic being done to derive `__dest`.
Anyway, what we're trying to express is that the size to copy from buf
is the size of the array pointed to by buf. However, buf is declared as
a pointer to uint8_t, which loses the length information. To fix that I
think we need:
- const uint8_t *buf;
+ const uint8_t (*buf)[4];
and then:
- nmi_scratch_append(nmi, buf, sizeof(buf));
+ nmi_scratch_append(nmi, buf, sizeof(*buf));
Andrew
