Add the __counted_by compiler attribute to the flexible array member inodes to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE.
Remove the now obsolete comment on the count field. Refactor ext4_expand_inode_array() by assigning count before copying any data using memcpy(). Copy only the inodes array instead of the whole struct because count has been set explicitly. Use struct_size() and struct_size_t() instead of offsetof(). Change the data type of the local variable count to unsigned int to match the struct's count data type. Compile-tested only. Signed-off-by: Thorsten Blum <thorsten.b...@toblux.com> --- Changes in v2: - Adjust ext4_expand_inode_array() as suggested by Gustavo A. R. Silva - Use struct_size() and struct_size_t() instead of offsetof() - Link to v1: https://lore.kernel.org/linux-kernel/20240729110454.346918-3-thorsten.b...@toblux.com/ --- fs/ext4/xattr.c | 20 +++++++++----------- fs/ext4/xattr.h | 4 ++-- 2 files changed, 11 insertions(+), 13 deletions(-) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 46ce2f21fef9..b27543587103 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -2879,11 +2879,10 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, if (*ea_inode_array == NULL) { /* * Start with 15 inodes, so it fits into a power-of-two size. - * If *ea_inode_array is NULL, this is essentially offsetof() */ (*ea_inode_array) = - kmalloc(offsetof(struct ext4_xattr_inode_array, - inodes[EIA_MASK]), + kmalloc(struct_size_t(struct ext4_xattr_inode_array, + inodes, EIA_MASK), GFP_NOFS); if (*ea_inode_array == NULL) return -ENOMEM; @@ -2891,17 +2890,16 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array, } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) { /* expand the array once all 15 + n * 16 slots are full */ struct ext4_xattr_inode_array *new_array = NULL; - int count = (*ea_inode_array)->count; + unsigned int count = (*ea_inode_array)->count; - /* if new_array is NULL, this is essentially offsetof() */ - new_array = kmalloc( - offsetof(struct ext4_xattr_inode_array, - inodes[count + EIA_INCR]), - GFP_NOFS); + new_array = kmalloc(struct_size(*ea_inode_array, inodes, + count + EIA_INCR), + GFP_NOFS); if (new_array == NULL) return -ENOMEM; - memcpy(new_array, *ea_inode_array, - offsetof(struct ext4_xattr_inode_array, inodes[count])); + new_array->count = count; + memcpy(new_array->inodes, (*ea_inode_array)->inodes, + count * sizeof(struct inode *)); kfree(*ea_inode_array); *ea_inode_array = new_array; } diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h index bd97c4aa8177..e14fb19dc912 100644 --- a/fs/ext4/xattr.h +++ b/fs/ext4/xattr.h @@ -130,8 +130,8 @@ struct ext4_xattr_ibody_find { }; struct ext4_xattr_inode_array { - unsigned int count; /* # of used items in the array */ - struct inode *inodes[]; + unsigned int count; + struct inode *inodes[] __counted_by(count); }; extern const struct xattr_handler ext4_xattr_user_handler; -- 2.45.2
