Add the __counted_by compiler attribute to the flexible array member b to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE.
Use struct_size() to calculate the number of bytes to be allocated. Update bucket_gens->nbuckets and bucket_gens->nbuckets_minus_first when resizing. Compile-tested only. Signed-off-by: Thorsten Blum <[email protected]> --- fs/bcachefs/buckets.c | 13 ++++++++----- fs/bcachefs/buckets_types.h | 2 +- 2 files changed, 9 insertions(+), 6 deletions(-) diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c index ec7d9a59bea9..8bd17667e243 100644 --- a/fs/bcachefs/buckets.c +++ b/fs/bcachefs/buckets.c @@ -1266,8 +1266,9 @@ int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets) BUG_ON(resize && ca->buckets_nouse); - if (!(bucket_gens = kvmalloc(sizeof(struct bucket_gens) + nbuckets, - GFP_KERNEL|__GFP_ZERO))) { + bucket_gens = kvmalloc(struct_size(bucket_gens, b, nbuckets), + GFP_KERNEL|__GFP_ZERO); + if (!bucket_gens) { ret = -BCH_ERR_ENOMEM_bucket_gens; goto err; } @@ -1285,11 +1286,13 @@ int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets) old_bucket_gens = rcu_dereference_protected(ca->bucket_gens, 1); if (resize) { - size_t n = min(bucket_gens->nbuckets, old_bucket_gens->nbuckets); - + bucket_gens->nbuckets = min(bucket_gens->nbuckets, + old_bucket_gens->nbuckets); + bucket_gens->nbuckets_minus_first = + bucket_gens->nbuckets - bucket_gens->first_bucket; memcpy(bucket_gens->b, old_bucket_gens->b, - n); + bucket_gens->nbuckets); } rcu_assign_pointer(ca->bucket_gens, bucket_gens); diff --git a/fs/bcachefs/buckets_types.h b/fs/bcachefs/buckets_types.h index 28bd09a253c8..7174047b8e92 100644 --- a/fs/bcachefs/buckets_types.h +++ b/fs/bcachefs/buckets_types.h @@ -24,7 +24,7 @@ struct bucket_gens { u16 first_bucket; size_t nbuckets; size_t nbuckets_minus_first; - u8 b[]; + u8 b[] __counted_by(nbuckets); }; struct bch_dev_usage { -- 2.47.0
