Commit 4bfbc269 authored by Thorsten Blum's avatar Thorsten Blum Committed by Kees Cook
Browse files

mux: Convert mux_control_ops to a flex array member in mux_chip 

Convert mux_control_ops to a flexible array member at the end of the
mux_chip struct and add the __counted_by() compiler attribute to
improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
CONFIG_FORTIFY_SOURCE.

Use struct_size() to calculate the number of bytes to allocate for a new
mux chip and to remove the following Coccinelle/coccicheck warning:

  WARNING: Use struct_size

Use size_add() to safely add any extra bytes.

No functional changes intended.

Link: https://github.com/KSPP/linux/issues/83


Signed-off-by: default avatarThorsten Blum <thorsten.blum@linux.dev>
Link: https://lore.kernel.org/r/20250610104106.1948-2-thorsten.blum@linux.dev


Signed-off-by: default avatarKees Cook <kees@kernel.org>
parent e04c78d8

drivers/mux/core.c

+3 −4
Original line number Diff line number Diff line
@@ -98,13 +98,12 @@ struct mux_chip *mux_chip_alloc(struct device *dev, 
	if (WARN_ON(!dev || !controllers))

		return ERR_PTR(-EINVAL);



	mux_chip = kzalloc(sizeof(*mux_chip) +

			   controllers * sizeof(*mux_chip->mux) +

			   sizeof_priv, GFP_KERNEL);

	mux_chip = kzalloc(size_add(struct_size(mux_chip, mux, controllers),

				    sizeof_priv),

			   GFP_KERNEL);

	if (!mux_chip)

		return ERR_PTR(-ENOMEM);



	mux_chip->mux = (struct mux_control *)(mux_chip + 1);

	mux_chip->dev.class = &mux_class;

	mux_chip->dev.type = &mux_type;

	mux_chip->dev.parent = dev;

include/linux/mux/driver.h

+2 −2
Original line number Diff line number Diff line
@@ -56,18 +56,18 @@ struct mux_control { 
/**

 * struct mux_chip -	Represents a chip holding mux controllers.

 * @controllers:	Number of mux controllers handled by the chip.

 * @mux:		Array of mux controllers that are handled.

 * @dev:		Device structure.

 * @id:			Used to identify the device internally.

 * @ops:		Mux controller operations.

 * @mux:		Array of mux controllers that are handled.

 */

struct mux_chip {

	unsigned int controllers;

	struct mux_control *mux;

	struct device dev;

	int id;



	const struct mux_control_ops *ops;

	struct mux_control mux[] __counted_by(controllers);

};



#define to_mux_chip(x) container_of((x), struct mux_chip, dev)