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R. Silva" , linux-kernel@vger.kernel.org (open list), linux-hardening@vger.kernel.org (open list:KERNEL HARDENING (not covered by other areas):Keyword:\b__counted_by(_le|_be)?\b) Subject: [PATCH 2/2] mtd: concat: replace alloc + calloc with 1 alloc Date: Wed, 4 Mar 2026 14:15:30 -0800 Message-ID: <20260304221530.15018-3-rosenp@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260304221530.15018-1-rosenp@gmail.com> References: <20260304221530.15018-1-rosenp@gmail.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A flex array can be used to reduce the allocation to 1. And actually mtdconcat was using the pointer + 1 trick to point to the overallocated area. Better alternatives exist. Signed-off-by: Rosen Penev --- drivers/mtd/mtd_virt_concat.c | 10 ++-------- drivers/mtd/mtdconcat.c | 5 +---- include/linux/mtd/concat.h | 2 +- 3 files changed, 4 insertions(+), 13 deletions(-) diff --git a/drivers/mtd/mtd_virt_concat.c b/drivers/mtd/mtd_virt_concat.c index 89e223edac6a..b56f2431974b 100644 --- a/drivers/mtd/mtd_virt_concat.c +++ b/drivers/mtd/mtd_virt_concat.c @@ -32,7 +32,7 @@ struct mtd_virt_concat_node { struct list_head head; unsigned int count; struct mtd_concat *concat; - struct device_node *nodes[] __counted_by(nodes); + struct device_node *nodes[] __counted_by(count); }; /** @@ -182,18 +182,12 @@ static int mtd_virt_concat_create_item(struct device_node *parts, for (i = 1; i < count; i++) item->nodes[i] = of_parse_phandle(parts, CONCAT_PROP, (i - 1)); - concat = kzalloc(sizeof(*concat), GFP_KERNEL); + concat = kzalloc_flex(*concat, subdev, count, GFP_KERNEL); if (!concat) { kfree(item); return -ENOMEM; } - concat->subdev = kcalloc(count, sizeof(*concat->subdev), GFP_KERNEL); - if (!concat->subdev) { - kfree(item); - kfree(concat); - return -ENOMEM; - } item->concat = concat; list_add_tail(&item->head, &concat_node_list); diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c index 241d15235d01..c97167d51fe2 100644 --- a/drivers/mtd/mtdconcat.c +++ b/drivers/mtd/mtdconcat.c @@ -627,7 +627,6 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[], /* subdevices to c const char *name) { /* name for the new device */ int i; - size_t size; struct mtd_concat *concat; struct mtd_info *subdev_master = NULL; uint32_t max_erasesize, curr_erasesize; @@ -640,15 +639,13 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[], /* subdevices to c printk(KERN_NOTICE "into device \"%s\"\n", name); /* allocate the device structure */ - size = SIZEOF_STRUCT_MTD_CONCAT(num_devs); - concat = kzalloc(size, GFP_KERNEL); + concat = kzalloc_flex(*concat, subdev, num_devs, GFP_KERNEL); if (!concat) { printk ("memory allocation error while creating concatenated device \"%s\"\n", name); return NULL; } - concat->subdev = (struct mtd_info **) (concat + 1); /* * Set up the new "super" device's MTD object structure, check for diff --git a/include/linux/mtd/concat.h b/include/linux/mtd/concat.h index 2cd9d48958a8..f8d4d6ac1fc1 100644 --- a/include/linux/mtd/concat.h +++ b/include/linux/mtd/concat.h @@ -18,7 +18,7 @@ struct mtd_concat { struct mtd_info mtd; int num_subdev; - struct mtd_info **subdev; + struct mtd_info *subdev[]; }; struct mtd_info *mtd_concat_create( -- 2.53.0