On 9/15/23 13:59, Kees Cook wrote:
Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).
As found with Coccinelle[1], add __counted_by for struct f_midi.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.
[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: John Keeping <john@xxxxxxxxxxxxx>
Cc: Peter Chen <peter.chen@xxxxxxx>
Cc: Hulk Robot <hulkci@xxxxxxxxxx>
Cc: Allen Pais <allen.lkml@xxxxxxxxx>
Cc: Will McVicker <willmcvicker@xxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Zhang Qilong <zhangqilong3@xxxxxxxxxx>
Cc: linux-usb@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Thanks
--
Gustavo
---
drivers/usb/gadget/function/f_midi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 2d02f25f9597..033e347554db 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -99,7 +99,7 @@ struct f_midi {
unsigned int in_last_port;
unsigned char free_ref;
- struct gmidi_in_port in_ports_array[/* in_ports */];
+ struct gmidi_in_port in_ports_array[] __counted_by(in_ports);
};
static inline struct f_midi *func_to_midi(struct usb_function *f)
@@ -1349,6 +1349,7 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
status = -ENOMEM;
goto setup_fail;
}
+ midi->in_ports = opts->in_ports;
for (i = 0; i < opts->in_ports; i++)
midi->in_ports_array[i].cable = i;
@@ -1359,7 +1360,6 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
status = -ENOMEM;
goto midi_free;
}
- midi->in_ports = opts->in_ports;
midi->out_ports = opts->out_ports;
midi->index = opts->index;
midi->buflen = opts->buflen;
