Messages in this thread | | | Date | Fri, 25 Nov 2022 19:48:01 +0200 | From | 'Andy Shevchenko' <> | Subject | Re: [PATCH 0/1] Slightly relax the type checking done by min() and max(). |
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On Fri, Nov 25, 2022 at 04:14:58PM +0000, David Laight wrote: > From: 'Andy Shevchenko' > > Sent: 25 November 2022 15:58 > > On Fri, Nov 25, 2022 at 03:27:07PM +0000, David Laight wrote:
...
> > Any better example, please? > > How about:
Better, indeed.
> data_size = min_t(u16, buf_size, len); > > https://elixir.bootlin.com/linux/v6.1-rc6/source/kernel/printk/printk_ringbuffer.c#L1738 > > Now, maybe, you could claim that buf_size > 64k never happens. > But the correct cast here is u32 to match buf_size. > len (being u16) will be promoted to int before the compare. > > Just search the kernel for "min_t(u8," or "min_t(u16," while some might > be ok, I really wouldn't want to verify each case. > > If you look hard enough there are also some: > u32_var = min_t(u32, u32_val, u64_val); > where the intent is to limit values that might be invalid for u32.
Wouldn't be better to actually issue a warning if the desired type is shorter than one of the min_t() arguments?
Then you go through all cases and fix them accordingly.
Blindly relaxing the rules is not an option in my opinion.
-- With Best Regards, Andy Shevchenko
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