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md/md-linear: Annotate struct linear_conf with __counted_by

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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: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230915200328.never.064-kees@kernel.org
This commit is contained in:
Kees Cook 2023-09-15 13:03:28 -07:00 committed by Song Liu
parent 54d21eb6ad
commit e887544d76
2 changed files with 14 additions and 14 deletions
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26
drivers/md/md-linear.c
View File

@ -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:

2
drivers/md/md-linear.h
View File

@ -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