In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memcpy(), memmove(), and memset(), avoid intentionally writing across neighboring fields.
Use struct_group() in struct cp2112_string_report around members report, length, type, and string, so they can be referenced together. This will allow memcpy() and sizeof() to more easily reason about sizes, improve readability, and avoid future warnings about writing beyond the end of report.
"pahole" shows no size nor member offset changes to struct cp2112_string_report. "objdump -d" shows no meaningful object code changes (i.e. only source line number induced differences.)
Signed-off-by: Kees Cook keescook@chromium.org --- drivers/hid/hid-cp2112.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c index 477baa30889c..e6ee453c7cfc 100644 --- a/drivers/hid/hid-cp2112.c +++ b/drivers/hid/hid-cp2112.c @@ -129,10 +129,12 @@ struct cp2112_xfer_status_report {
struct cp2112_string_report { u8 dummy; /* force .string to be aligned */ - u8 report; /* CP2112_*_STRING */ - u8 length; /* length in bytes of everyting after .report */ - u8 type; /* USB_DT_STRING */ - wchar_t string[30]; /* UTF16_LITTLE_ENDIAN string */ + struct_group_attr(contents, __packed, + u8 report; /* CP2112_*_STRING */ + u8 length; /* length in bytes of everyting after .report */ + u8 type; /* USB_DT_STRING */ + wchar_t string[30]; /* UTF16_LITTLE_ENDIAN string */ + ); } __packed;
/* Number of times to request transfer status before giving up waiting for a @@ -986,8 +988,8 @@ static ssize_t pstr_show(struct device *kdev, u8 length; int ret;
- ret = cp2112_hid_get(hdev, attr->report, &report.report, - sizeof(report) - 1, HID_FEATURE_REPORT); + ret = cp2112_hid_get(hdev, attr->report, (u8 *)&report.contents, + sizeof(report.contents), HID_FEATURE_REPORT); if (ret < 3) { hid_err(hdev, "error reading %s string: %d\n", kattr->attr.name, ret);