On 10/30/24 5:40 AM, Dan Carpenter wrote:
> Hello Jens Axboe,
>
> Commit 4b926ab18279 ("io_uring: add support for fixed wait regions")
> from Oct 22, 2024 (linux-next), leads to the following Smatch static
> checker warning:
>
> io_uring/register.c:616 io_register_cqwait_reg()
> warn: was expecting a 64 bit value instead of '~(~(((1) << 12) - 1))'
>
> io_uring/register.c
> 594 static int io_register_cqwait_reg(struct io_ring_ctx *ctx, void __user *uarg)
> 595 {
> 596 struct io_uring_cqwait_reg_arg arg;
> 597 struct io_uring_reg_wait *reg;
> 598 struct page **pages;
> 599 unsigned long len;
> 600 int nr_pages, poff;
> 601 int ret;
> 602
> 603 if (ctx->cq_wait_page || ctx->cq_wait_arg)
> 604 return -EBUSY;
> 605 if (copy_from_user(&arg, uarg, sizeof(arg)))
> 606 return -EFAULT;
> 607 if (!arg.nr_entries || arg.flags)
> 608 return -EINVAL;
> 609 if (arg.struct_size != sizeof(*reg))
> 610 return -EINVAL;
> 611 if (check_mul_overflow(arg.struct_size, arg.nr_entries, &len))
> 612 return -EOVERFLOW;
> 613 if (len > PAGE_SIZE)
> 614 return -EINVAL;
> 615 /* offset + len must fit within a page, and must be reg_wait aligned */
> --> 616 poff = arg.user_addr & ~PAGE_MASK;
>
> This is a harmless thing, but on 32 bit systems you can put whatever you want in
> the high 32 bits of arg.user_addr and it won't affect anything.
That is certainly true, it'll get masked away. I suspect this kind of
thing is everywhere, though? What do you suggest?
--
Jens Axboe
