UBSAN can insert extra code in random locations; including AC=1 sections. Typically this code is not safe and needs wrapping.
So far, only __ubsan_handle_type_mismatch* have been observed in AC=1 sections and therefore only those are annotated. Cc: Dmitry Vyukov <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> --- lib/Makefile | 1 + lib/ubsan.c | 4 ++++ 2 files changed, 5 insertions(+) --- a/lib/Makefile +++ b/lib/Makefile @@ -263,6 +263,7 @@ obj-$(CONFIG_UCS2_STRING) += ucs2_string obj-$(CONFIG_UBSAN) += ubsan.o UBSAN_SANITIZE_ubsan.o := n +CFLAGS_ubsan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) obj-$(CONFIG_SBITMAP) += sbitmap.o --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -17,6 +17,7 @@ #include <linux/kernel.h> #include <linux/types.h> #include <linux/sched.h> +#include <linux/uaccess.h> #include "ubsan.h" @@ -313,6 +314,7 @@ static void handle_object_size_mismatch( static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, unsigned long ptr) { + unsigned long flags = user_access_save(); if (!ptr) handle_null_ptr_deref(data); @@ -320,6 +322,8 @@ static void ubsan_type_mismatch_common(s handle_misaligned_access(data, ptr); else handle_object_size_mismatch(data, ptr); + + user_access_restore(flags); } void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
