On Tue, Aug 13, 2024 at 1:51 PM Thorsten Blum <thorsten.blum@xxxxxxxxxx> wrote: > > On 13. Aug 2024, at 20:57, Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote: > > On Tue, Aug 13, 2024 at 10:59 AM Thorsten Blum <thorsten.blum@xxxxxxxxxx> wrote: > >> On 13. Aug 2024, at 18:28, Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote: > >>> On Tue, Aug 13, 2024 at 8:19 AM Thorsten Blum <thorsten.blum@xxxxxxxxxx> wrote: > >>>> > >>>> Add the __counted_by compiler attribute to the flexible array member > >>>> cands to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and > >>>> CONFIG_FORTIFY_SOURCE. > >>>> > >>>> Increment cnt before adding a new struct to the cands array. > >>> > >>> why? What happens otherwise? > >> > >> If you try to access cands->cands[cands->cnt] without incrementing > >> cands->cnt first, you're essentially accessing the array out of bounds > >> which will fail during runtime. > > > > What kind of error/warn do you see ? > > Is it runtime or compile time? > > I get a runtime error with Clang 18 [3]. ... > [3] https://godbolt.org/z/cKee95777 This is user space. I'm not asking about generic description of the counted_by feature. I want to see the actual runtime report from the kernel. Can it even compile the kernel with -fsanitize=undefined ? pw-bot: cr
