From f9409d58e972cada2c524b7f1e54631bb8fa176f Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Thu, 6 Aug 2020 23:25:05 -0700 Subject: [PATCH] kasan, arm64: don't instrument functions that enable kasan This patch prepares Software Tag-Based KASAN for stack tagging support. With stack tagging enabled, KASAN tags stack variable in each function in its prologue. In start_kernel() stack variables get tagged before KASAN is enabled via setup_arch()->kasan_init(). As the result the tags for start_kernel()'s stack variables end up in the temporary shadow memory. Later when KASAN gets enabled, switched to normal shadow, and starts checking tags, this leads to false-positive reports, as proper tags are missing in normal shadow. Disable KASAN instrumentation for start_kernel(). Also disable it for arm64's setup_arch() as a precaution (it doesn't have any stack variables right now). [andreyknvl@google.com: reorder attributes for start_kernel()] Link: http://lkml.kernel.org/r/26fb6165a17abcf61222eda5184c030fb6b133d1.1596544734.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Signed-off-by: Andrew Morton Acked-by: Catalin Marinas [arm64] Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Elena Petrova Cc: Marco Elver Cc: Vincenzo Frascino Cc: Walter Wu Cc: Ard Biesheuvel Link: http://lkml.kernel.org/r/55d432671a92e931ab8234b03dc36b14d4c21bfb.1596199677.git.andreyknvl@google.com Signed-off-by: Linus Torvalds --- arch/arm64/kernel/setup.c | 2 +- init/main.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index c793276ec7ad..87e81d29e6fb 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -276,7 +276,7 @@ arch_initcall(reserve_memblock_reserved_regions); u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID }; -void __init setup_arch(char **cmdline_p) +void __init __no_sanitize_address setup_arch(char **cmdline_p) { init_mm.start_code = (unsigned long) _text; init_mm.end_code = (unsigned long) _etext; diff --git a/init/main.c b/init/main.c index 15bd0efff3df..92d25796ae9d 100644 --- a/init/main.c +++ b/init/main.c @@ -829,7 +829,7 @@ void __init __weak arch_call_rest_init(void) rest_init(); } -asmlinkage __visible void __init start_kernel(void) +asmlinkage __visible void __init __no_sanitize_address start_kernel(void) { char *command_line; char *after_dashes;