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usb: Annotate struct urb_priv with __counted_by

PATCH Applied Kees Cook 2 participants 3 messages Sep 15, 2023 – Oct 2, 2023

Subsystems (3)
USB USB xHCI driver USB ohci driver
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Kees Cook

author
#0 lore raw

PATCH 1/1 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 <[email protected]>
Cc Greg Kroah-Hartman <[email protected]>
Cc Mathias Nyman <[email protected]>
Cc [email protected]
Signed-off-by Kees Cook <[email protected]>
---
 drivers/usb/host/ohci.h | 2 +-
 drivers/usb/host/xhci.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
drivers/usb/host/ohci.h +1 -1
index aac6285b37f8..1aba22784e05 100644
@@ -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;
drivers/usb/host/xhci.h +1 -1
index 7e282b4522c0..2f21c3a8565c 100644
@@ -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);
 };
 
 /*
Signature · 1 line
2.34.1
author Applied
#1 lore raw
Quoted 9 lines · Kees Cook

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.

[...]

Applied to for-next/hardening, thanks!

[1/1] usb: Annotate struct urb_priv with __counted_by

      https://git.kernel.org/kees/c/a5683963b3f5

Take care,

Signature · 1 line
Kees Cook
maintainer
#2 lore raw
In reply to Kees Cook
Quoted 15 lines · Kees Cook

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 <[email protected]>
Cc Greg Kroah-Hartman <[email protected]>
Cc Mathias Nyman <[email protected]>
Cc [email protected]
Signed-off-by Kees Cook <[email protected]>
Quoted 4 lines
---
 drivers/usb/host/ohci.h | 2 +-
 drivers/usb/host/xhci.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Thanks for taking these changes through your tree, I was too slow...

greg k-h