| Message ID | 20220516194241.3064242-1-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | sched/core: Do not treat class list boundary markers as arrays | expand |
On Mon, May 16, 2022 at 12:42:41PM -0700, Kees Cook wrote: > GCC 12 is very sensitive about array checking, and views all negative > array accesses as unsafe (a not unreasonable position). Avoid the > warnings about __begin_sched_classes being accessed via negative bounds > by converting them to the pointers they actually are. Silences this > warning: Yeah, this patch is *much* saner, thanks! > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 8dccb34eb190..3d31ed9d33fa 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -2190,8 +2190,8 @@ const struct sched_class name##_sched_class \ > __section("__" #name "_sched_class") > > /* Defined in include/asm-generic/vmlinux.lds.h */ > -extern struct sched_class __begin_sched_classes[]; > -extern struct sched_class __end_sched_classes[]; > +extern struct sched_class *__begin_sched_classes; > +extern struct sched_class *__end_sched_classes; > > #define sched_class_highest (__end_sched_classes - 1) > #define sched_class_lowest (__begin_sched_classes - 1) > -- > 2.32.0 >
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 8dccb34eb190..3d31ed9d33fa 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2190,8 +2190,8 @@ const struct sched_class name##_sched_class \ __section("__" #name "_sched_class") /* Defined in include/asm-generic/vmlinux.lds.h */ -extern struct sched_class __begin_sched_classes[]; -extern struct sched_class __end_sched_classes[]; +extern struct sched_class *__begin_sched_classes; +extern struct sched_class *__end_sched_classes; #define sched_class_highest (__end_sched_classes - 1) #define sched_class_lowest (__begin_sched_classes - 1)
GCC 12 is very sensitive about array checking, and views all negative array accesses as unsafe (a not unreasonable position). Avoid the warnings about __begin_sched_classes being accessed via negative bounds by converting them to the pointers they actually are. Silences this warning: In file included from kernel/sched/core.c:81: kernel/sched/core.c: In function ‘set_rq_online.part.0’: kernel/sched/sched.h:2197:52: error: array subscript -1 is outside array bounds of ‘struct sched_class[44343134792571037]’ [-Werror=array-bounds] 2197 | #define sched_class_lowest (__begin_sched_classes - 1) | ^ kernel/sched/sched.h:2200:41: note: in definition of macro ‘for_class_range’ 2200 | for (class = (_from); class != (_to); class--) | ^~~ kernel/sched/sched.h:2203:53: note: in expansion of macro ‘sched_class_lowest’ 2203 |for_class_range(class, sched_class_highest, sched_class_lowest) | ^~~~~~~~~~~~~~~~~~ kernel/sched/core.c:9115:17: note: in expansion of macro ‘for_each_class’ 9115 | for_each_class(class) { | ^~~~~~~~~~~~~~ kernel/sched/sched.h:2193:27: note: at offset -208 into object ‘__begin_sched_classes’ of size [0, 9223372036854775807] 2193 | extern struct sched_class __begin_sched_classes[]; | ^~~~~~~~~~~~~~~~~~~~~ Reported-by: Christophe de Dinechin <dinechin@redhat.com> Link: https://lore.kernel.org/lkml/20220414150855.2407137-2-dinechin@redhat.com/ Cc: Ingo Molnar <mingo@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ben Segall <bsegall@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Kees Cook <keescook@chromium.org> --- kernel/sched/sched.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)