Re: [Xen-devel] UBSAN report in find_next_bit()

[Julien Grall <julien.grall@xxxxxxx>]

Hi Jan,

On 25/06/2019 10:38, Jan Beulich wrote:
> > > > On 24.06.19 at 18:24, <andrew.cooper3@xxxxxxxxxx> wrote:
> > ARM64's find_next_bit() explicitly copes with offset >= size, and while
> > I don't speak ARM asm well enough to work out whether
> > _find_first_bit_le() copes with offset == size, the vgic.c code
> > definitely expects it to function in this way.
> ... Arm32's _find_next{,_zero}_bit_le. You've named the issue the x86
> logic has. Arm32's, afaict, will read one byte past the array when offset
> and size match and are a multiple of 8.
It took me a bit to get my head around as the code is quite convoluted. But I 
agree with you here, arm32 find_* does not cope with offset == size.
Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel