usb: Annotate struct urb_priv with __counted_by

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 urb_priv.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: linux-usb@vger.kernel.org
Link: https://lore.kernel.org/r/20230915195812.never.371-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/drivers/usb/host/ohci.h b/drivers/usb/host/ohci.h
index aac6285b37f80d3465eb7ee6453c5d2dc52a59b2..631dda6174b4542608d76ec7083d10aac6eccf85 100644 (file)
--- a/drivers/usb/host/ohci.h
+++ b/drivers/usb/host/ohci.h
@@ -337,7 +337,7 @@ typedef struct urb_priv {
        u16                     length;         // # tds in this request
        u16                     td_cnt;         // tds already serviced
        struct list_head        pending;
-       struct td               *td[];          // all TDs in this request
+       struct td               *td[] __counted_by(length); // all TDs in this request
 
 } urb_priv_t;
 

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 7e282b4522c0aa16c15398afefb933ecec2db7e5..2f21c3a8565c79773ac066a6b45dcc194b3c7d4f 100644 (file)
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1666,7 +1666,7 @@ struct xhci_scratchpad {
 struct urb_priv {
        int     num_tds;
        int     num_tds_done;
-       struct  xhci_td td[];
+       struct  xhci_td td[] __counted_by(num_tds);
 };
 
 /*