| Message ID | 55d432671a92e931ab8234b03dc36b14d4c21bfb.1596199677.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kasan: support stack instrumentation for tag-based mode | expand |
On Fri, Jul 31, 2020 at 03:20:39PM +0200, Andrey Konovalov wrote: > 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). > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> For arm64: Acked-by: Catalin Marinas <catalin.marinas@arm.com>
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 2d74985e09b1..c73a16ff213e 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 __no_sanitize_address void __init start_kernel(void) { char *command_line; char *after_dashes;
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). Signed-off-by: Andrey Konovalov <andreyknvl@google.com> --- arch/arm64/kernel/setup.c | 2 +- init/main.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)