Messages in this thread | | | Subject | Re: [PATCH] init/Kconfig: extend -Wno-array-bounds to gcc 13 | From | Tom Rix <> | Date | Mon, 6 Mar 2023 17:07:42 -0800 |
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On 3/6/23 3:02 PM, Kees Cook wrote: > On March 6, 2023 2:20:50 PM PST, Nick Desaulniers <ndesaulniers@google.com> wrote: >> + Kees >> https://lore.kernel.org/lkml/20230306220947.1982272-1-trix@redhat.com/ >> >> On Mon, Mar 6, 2023 at 2:10 PM Tom Rix <trix@redhat.com> wrote: >>> With gcc 13.0.1 on x86, there are several false positives like >>> >>> drivers/net/ethernet/microchip/sparx5/sparx5_psfp.c:167:31: >>> error: array subscript 4 is above array bounds of ‘const struct sparx5_psfp_gce[4]’ [-Werror=array-bounds=] >>> 167 | gce = &sg->gce[i]; >>> | ~~~~~~~^~~ >>> In file included from drivers/net/ethernet/microchip/sparx5/sparx5_psfp.c:8: >>> drivers/net/ethernet/microchip/sparx5/sparx5_main.h:506:32: note: while referencing ‘gce’ >>> 506 | struct sparx5_psfp_gce gce[SPX5_PSFP_GCE_CNT]; >>> | ^~~ >>> >>> The code lines for the reported problem >>> /* For each scheduling entry */ >>> for (i = 0; i < sg->num_entries; i++) { >>> gce = &sg->gce[i]; >>> >>> i is bounded by num_entries, which is set in sparx5_tc_flower.c >>> if (act->gate.num_entries >= SPX5_PSFP_GCE_CNT) { >>> NL_SET_ERR_MSG_MOD(extack, "Invalid number of gate entries"); >>> return -EINVAL; >>> } >>> .. >>> sg->num_entries = act->gate.num_entries; >>> >>> So disable array-bounds as was done on gcc 11 and 12 > GCC 13 isn't released yet, and we've been working to make Linux warning-free under -Wareay-bounds. (And we succeeded briefly with GCC 11.) > > I'd much rather get GCC fixed. This is due to the shift sanitizer reducing the scope of num_entries (via macro args) to 0-31, which is still >4. This seems like a hinting bug in GCC: just because the variable was used in a shift doesn't mean the compiler can make any value assumptions.
The build with fail generally with gcc 13.
The warnings could be cleaned without having an error, but I looked at multiple errors, none of them were real.
imo this is a broken compiler option.
Tom
> > -Kees > > >
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