| Message ID | 20210825160749.3891090-1-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | [RFC] platform/x86: dell-smbios-wmi: Avoid false-positive memcpy() warning | expand |
On Wed, Aug 25, 2021 at 09:07:49AM -0700, Kees Cook wrote: > 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. > > Since all the size checking has already happened, use input.pointer > (void *) so memcpy() doesn't get confused about how much is being > written. > > Avoids this false-positive warning when run-time memcpy() strict > bounds checking is enabled: > > memcpy: detected field-spanning write (size 4096) of single field (size 36) > WARNING: CPU: 0 PID: 357 at drivers/platform/x86/dell/dell-smbios-wmi.c:74 run_smbios_call+0x110/0x1e0 [dell_smbios] > Note: is there a missed kfree() in the marked error path? Seems so. * Note: The caller should use acpi_os_free to free this * buffer created via ACPI_ALLOCATE_BUFFER.
Hi, On 8/25/21 6:07 PM, Kees Cook wrote: > 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. > > Since all the size checking has already happened, use input.pointer > (void *) so memcpy() doesn't get confused about how much is being > written. > > Avoids this false-positive warning when run-time memcpy() strict > bounds checking is enabled: > > memcpy: detected field-spanning write (size 4096) of single field (size 36) > WARNING: CPU: 0 PID: 357 at drivers/platform/x86/dell/dell-smbios-wmi.c:74 run_smbios_call+0x110/0x1e0 [dell_smbios] > > Note: is there a missed kfree() in the marked error path? > > Cc: Hans de Goede <hdegoede@redhat.com> > Cc: Mark Gross <mgross@linux.intel.com> > Cc: Mario Limonciello <mario.limonciello@dell.com> > Cc: "Pali Rohár" <pali@kernel.org> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de> > Cc: Dell.Client.Kernel@dell.com > Cc: platform-driver-x86@vger.kernel.org > Reported-by: Andy Lavr <andy.lavr@gmail.com> > Signed-off-by: Kees Cook <keescook@chromium.org> Thank you, I've applied the patch, minus the: /* output.pointer memory allocation leak? */ Comment, instead I'll submit (and also apply right-away) a patch to add the missing kfree() Regards, Hans > --- > drivers/platform/x86/dell/dell-smbios-wmi.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/platform/x86/dell/dell-smbios-wmi.c b/drivers/platform/x86/dell/dell-smbios-wmi.c > index 33f823772733..c410d6d920b8 100644 > --- a/drivers/platform/x86/dell/dell-smbios-wmi.c > +++ b/drivers/platform/x86/dell/dell-smbios-wmi.c > @@ -69,9 +69,10 @@ static int run_smbios_call(struct wmi_device *wdev) > if (obj->type == ACPI_TYPE_INTEGER) > dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n", > obj->integer.value); > + /* output.pointer memory allocation leak? */ > return -EIO; > } > - memcpy(&priv->buf->std, obj->buffer.pointer, obj->buffer.length); > + memcpy(input.pointer, obj->buffer.pointer, obj->buffer.length); > dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n", > priv->buf->std.output[0], priv->buf->std.output[1], > priv->buf->std.output[2], priv->buf->std.output[3]); >
diff --git a/drivers/platform/x86/dell/dell-smbios-wmi.c b/drivers/platform/x86/dell/dell-smbios-wmi.c index 33f823772733..c410d6d920b8 100644 --- a/drivers/platform/x86/dell/dell-smbios-wmi.c +++ b/drivers/platform/x86/dell/dell-smbios-wmi.c @@ -69,9 +69,10 @@ static int run_smbios_call(struct wmi_device *wdev) if (obj->type == ACPI_TYPE_INTEGER) dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n", obj->integer.value); + /* output.pointer memory allocation leak? */ return -EIO; } - memcpy(&priv->buf->std, obj->buffer.pointer, obj->buffer.length); + memcpy(input.pointer, obj->buffer.pointer, obj->buffer.length); dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n", priv->buf->std.output[0], priv->buf->std.output[1], priv->buf->std.output[2], priv->buf->std.output[3]);
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. Since all the size checking has already happened, use input.pointer (void *) so memcpy() doesn't get confused about how much is being written. Avoids this false-positive warning when run-time memcpy() strict bounds checking is enabled: memcpy: detected field-spanning write (size 4096) of single field (size 36) WARNING: CPU: 0 PID: 357 at drivers/platform/x86/dell/dell-smbios-wmi.c:74 run_smbios_call+0x110/0x1e0 [dell_smbios] Note: is there a missed kfree() in the marked error path? Cc: Hans de Goede <hdegoede@redhat.com> Cc: Mark Gross <mgross@linux.intel.com> Cc: Mario Limonciello <mario.limonciello@dell.com> Cc: "Pali Rohár" <pali@kernel.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de> Cc: Dell.Client.Kernel@dell.com Cc: platform-driver-x86@vger.kernel.org Reported-by: Andy Lavr <andy.lavr@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/platform/x86/dell/dell-smbios-wmi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)