Commit e887544d authored by Kees Cook's avatar Kees Cook Committed by Song Liu
Browse files

md/md-linear: Annotate struct linear_conf 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 linear_conf.
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: Song Liu <song@kernel.org>
Cc: linux-raid@vger.kernel.org
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230915200328.never.064-kees@kernel.org
parent 54d21eb6

drivers/md/md-linear.c

+13 −13
Original line number Diff line number Diff line
@@ -69,6 +69,19 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks) 
	if (!conf)

		return NULL;



	/*

	 * conf->raid_disks is copy of mddev->raid_disks. The reason to

	 * keep a copy of mddev->raid_disks in struct linear_conf is,

	 * mddev->raid_disks may not be consistent with pointers number of

	 * conf->disks[] when it is updated in linear_add() and used to

	 * iterate old conf->disks[] earray in linear_congested().

	 * Here conf->raid_disks is always consitent with number of

	 * pointers in conf->disks[] array, and mddev->private is updated

	 * with rcu_assign_pointer() in linear_addr(), such race can be

	 * avoided.

	 */

	conf->raid_disks = raid_disks;



	cnt = 0;

	conf->array_sectors = 0;
@@ -112,19 +125,6 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks) 
			conf->disks[i-1].end_sector +

			conf->disks[i].rdev->sectors;



	/*

	 * conf->raid_disks is copy of mddev->raid_disks. The reason to

	 * keep a copy of mddev->raid_disks in struct linear_conf is,

	 * mddev->raid_disks may not be consistent with pointers number of

	 * conf->disks[] when it is updated in linear_add() and used to

	 * iterate old conf->disks[] earray in linear_congested().

	 * Here conf->raid_disks is always consitent with number of

	 * pointers in conf->disks[] array, and mddev->private is updated

	 * with rcu_assign_pointer() in linear_addr(), such race can be

	 * avoided.

	 */

	conf->raid_disks = raid_disks;



	return conf;



out:

drivers/md/md-linear.h

+1 −1
Original line number Diff line number Diff line
@@ -12,6 +12,6 @@ struct linear_conf 
	struct rcu_head		rcu;

	sector_t		array_sectors;

	int			raid_disks; /* a copy of mddev->raid_disks */

	struct dev_info		disks[];

	struct dev_info		disks[] __counted_by(raid_disks);

};

#endif