Messages in this thread | | | Date | Thu, 17 Aug 2023 11:23:38 -0600 | Subject | Re: [PATCH v2][next] cgroup: Avoid -Wstringop-overflow warnings | From | "Gustavo A. R. Silva" <> |
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On 8/16/23 15:01, Tejun Heo wrote: > On Wed, Aug 16, 2023 at 01:57:16PM -0700, Kees Cook wrote: >> On Wed, Aug 16, 2023 at 10:51:12AM -1000, Tejun Heo wrote: >>> Hello, >>> >>> On Wed, Aug 16, 2023 at 02:50:16PM -0600, Gustavo A. R. Silva wrote: >>>> Change the notation from pointer-to-array to pointer-to-pointer. >>>> With this, we avoid the compiler complaining about trying >>>> to access a region of size zero as an argument during function >>>> calls. >>> >>> Haha, I thought the functions were actually accessing the memory. This can't >>> be an intended behavior on the compiler's side, right? >> >> I think it's a result of inlining -- the compiler ends up with a case >> where it looks like it might be possible to index a zero-sized array, >> but it is "accidentally safe". > > Ah I see. It's not that the compiler knows that ** access is safe. It's more > that it only applies the check on arrays. Is that right? Gustavo, I don't
That's correct.
> mind the patch but can you update the patch description a bit explaining a > bit more on what's going on with the complier? It doesn't have to be the > full explanation but it'd be useful to explicitly point out that we're just > working around the compiler being a bit silly.
I just sent v3:
https://lore.kernel.org/linux-hardening/ZN5WkbPelHUSTXOA@work/
Thanks -- Gustavo
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