On Sat, 14 Oct 2023, Kees Cook wrote: > On Sat, Oct 14, 2023 at 08:34:53AM +0200, Christophe JAILLET wrote: > > Prepare for the coming implementation by GCC and Clang of the __counted_by > > attribute. Flexible array members annotated with __counted_by can have > > their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS > > (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family > > functions). > > > > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> > > --- > > v2: Fix the subject [Ilya Maximets] > > fix the field name used with __counted_by [Ilya Maximets] > > > > v1: https://lore.kernel.org/all/f66ddcf1ef9328f10292ea75a17b584359b6cde3.1696156198.git.christophe.jaillet@xxxxxxxxxx/ > > > > > > This patch is part of a work done in parallel of what is currently worked > > on by Kees Cook. > > > > My patches are only related to corner cases that do NOT match the > > semantic of his Coccinelle script[1]. What was the problem with the semantic patch in this case? thanks, julia > > > > In this case, in tbl_mask_array_alloc(), several things are allocated with > > a single allocation. Then, some pointer arithmetic computes the address of > > the memory after the flex-array. > > > > [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci > > --- > > net/openvswitch/flow_table.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/net/openvswitch/flow_table.h b/net/openvswitch/flow_table.h > > index 9e659db78c05..f524dc3e4862 100644 > > --- a/net/openvswitch/flow_table.h > > +++ b/net/openvswitch/flow_table.h > > @@ -48,7 +48,7 @@ struct mask_array { > > int count, max; > > struct mask_array_stats __percpu *masks_usage_stats; > > u64 *masks_usage_zero_cntr; > > - struct sw_flow_mask __rcu *masks[]; > > + struct sw_flow_mask __rcu *masks[] __counted_by(max); > > }; > > Yup, this looks correct to me. Thanks! > > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > > -- > Kees Cook >
