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 <st...@rowland.harvard.edu>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Mathias Nyman <mathias.ny...@intel.com>
Cc: linux-...@vger.kernel.org
Signed-off-by: Kees Cook <keesc...@chromium.org>
---
 drivers/usb/host/ohci.h | 2 +-
 drivers/usb/host/xhci.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/ohci.h b/drivers/usb/host/ohci.h
index aac6285b37f8..1aba22784e05 100644
--- 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 7e282b4522c0..2f21c3a8565c 100644
--- 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);
 };
 
 /*
-- 
2.34.1

Reply via email to