On Thu, May 9, 2024 at 8:53 AM Jan Kara <jack@xxxxxxx> wrote: > > @@ -319,8 +320,12 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len) > > if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) > > return -ENODEV; > > > > - /* Check for wrap through zero too */ > > - if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) > > + /* Check for wraparound */ > > + if (check_add_overflow(offset, len, &sum)) > > + return -EFBIG; > > + > > + /* Now, check bounds */ > > + if (sum > inode->i_sb->s_maxbytes || sum < 0) > > return -EFBIG; > > But why do you check for sum < 0? We know from previous checks offset >= 0 > && len > 0 so unless we overflow, sum is guaranteed to be > 0. Fair enough. I suppose with the overflow check in place we can no longer have a sum less than zero there. If nothing else, it tells readers of this code what the domain of (offset+len) is. I don't mind sending a new version, though. > > Honza > -- > Jan Kara <jack@xxxxxxxx> > SUSE Labs, CR
