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 via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions).
While there, use struct_size() helper, instead of the open-coded version. Signed-off-by: Gustavo A. R. Silva <[email protected]> --- fs/fhandle.c | 8 ++++---- include/linux/fs.h | 2 +- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/fhandle.c b/fs/fhandle.c index 57a12614addf..53ed54711cd2 100644 --- a/fs/fhandle.c +++ b/fs/fhandle.c @@ -36,7 +36,7 @@ static long do_sys_name_to_handle(const struct path *path, if (f_handle.handle_bytes > MAX_HANDLE_SZ) return -EINVAL; - handle = kzalloc(sizeof(struct file_handle) + f_handle.handle_bytes, + handle = kzalloc(struct_size(handle, f_handle, f_handle.handle_bytes), GFP_KERNEL); if (!handle) return -ENOMEM; @@ -71,7 +71,7 @@ static long do_sys_name_to_handle(const struct path *path, /* copy the mount id */ if (put_user(real_mount(path->mnt)->mnt_id, mnt_id) || copy_to_user(ufh, handle, - sizeof(struct file_handle) + handle_bytes)) + struct_size(handle, f_handle, handle_bytes))) retval = -EFAULT; kfree(handle); return retval; @@ -192,7 +192,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh, retval = -EINVAL; goto out_err; } - handle = kmalloc(sizeof(struct file_handle) + f_handle.handle_bytes, + handle = kmalloc(struct_size(handle, f_handle, f_handle.handle_bytes), GFP_KERNEL); if (!handle) { retval = -ENOMEM; @@ -202,7 +202,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh, *handle = f_handle; if (copy_from_user(&handle->f_handle, &ufh->f_handle, - f_handle.handle_bytes)) { + struct_size(ufh, f_handle, f_handle.handle_bytes))) { retval = -EFAULT; goto out_handle; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 034f0c918eea..1540e28d10d7 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1033,7 +1033,7 @@ struct file_handle { __u32 handle_bytes; int handle_type; /* file identifier */ - unsigned char f_handle[]; + unsigned char f_handle[] __counted_by(handle_bytes); }; static inline struct file *get_file(struct file *f) -- 2.34.1
