From 2f088dfc1878108748018af0d2e3748ba9eee1e9 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 12 May 2023 14:22:12 -0700 Subject: [PATCH] md/raid5: Convert stripe_head's "dev" to flexible array member Replace old-style 1-element array of "dev" in struct stripe_head with modern C99 flexible array. In the future, we can additionally annotate it with the run-time size, found in the "disks" member. Cc: Song Liu Cc: linux-raid@vger.kernel.org Reviewed-by: Christoph Hellwig Acked-by: Song Liu Signed-off-by: Kees Cook Link: https://lore.kernel.org/lkml/20230522212114.gonna.589-kees@kernel.org/ --- It looks like this memory calculation: memory = conf->min_nr_stripes * (sizeof(struct stripe_head) + max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024; ... was already buggy (i.e. it included the single "dev" bytes in the result). However, I'm not entirely sure if that is the right analysis, since "dev" is not related to struct bio nor PAGE_SIZE? --- drivers/md/raid5.c | 4 ++-- drivers/md/raid5.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 4739ed8..64865f9 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2433,7 +2433,7 @@ static int grow_stripes(struct r5conf *conf, int num) conf->active_name = 0; sc = kmem_cache_create(conf->cache_name[conf->active_name], - sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev), + struct_size_t(struct stripe_head, dev, devs), 0, 0, NULL); if (!sc) return 1; @@ -2559,7 +2559,7 @@ static int resize_stripes(struct r5conf *conf, int newsize) /* Step 1 */ sc = kmem_cache_create(conf->cache_name[1-conf->active_name], - sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev), + struct_size_t(struct stripe_head, dev, newsize), 0, 0, NULL); if (!sc) return -ENOMEM; diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h index e873938..6a92faf 100644 --- a/drivers/md/raid5.h +++ b/drivers/md/raid5.h @@ -268,7 +268,7 @@ struct stripe_head { unsigned long flags; u32 log_checksum; unsigned short write_hint; - } dev[1]; /* allocated with extra space depending of RAID geometry */ + } dev[]; /* allocated depending of RAID geometry ("disks" member) */ }; /* stripe_head_state - collects and tracks the dynamic state of a stripe_head -- 2.7.4