When boot arm64 kernel with KASAN enabled, the below error is reported by kasan:

BUG: KASAN: out-of-bounds in unwind_frame+0xec/0x260 at addr ffffffc064d57ba0 Read of size 8 by task pidof/499 page:ffffffbdc39355c0 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x0() page dumped because: kasan: bad access detected CPU: 2 PID: 499 Comm: pidof Not tainted 4.5.0-rc1 #119 Hardware name: Freescale Layerscape 2085a RDB Board (DT) Call trace: [<ffffffc00008d078>] dump_backtrace+0x0/0x290 [<ffffffc00008d32c>] show_stack+0x24/0x30 [<ffffffc0006a981c>] dump_stack+0x8c/0xd8 [<ffffffc0002e4400>] kasan_report_error+0x558/0x588 [<ffffffc0002e4958>] kasan_report+0x60/0x70 [<ffffffc0002e3188>] __asan_load8+0x60/0x78 [<ffffffc00008c92c>] unwind_frame+0xec/0x260 [<ffffffc000087e60>] get_wchan+0x110/0x160 [<ffffffc0003b647c>] do_task_stat+0xb44/0xb68 [<ffffffc0003b7730>] proc_tgid_stat+0x40/0x50 [<ffffffc0003ac840>] proc_single_show+0x88/0xd8 [<ffffffc000345be8>] seq_read+0x370/0x770 [<ffffffc00030aba0>] __vfs_read+0xc8/0x1d8 [<ffffffc00030c0ec>] vfs_read+0x94/0x168 [<ffffffc00030d458>] SyS_read+0xb8/0x128 [<ffffffc000086530>] el0_svc_naked+0x24/0x28 Memory state around the buggy address: ffffffc064d57a80: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 f4 f4 ffffffc064d57b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

ffffffc064d57b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

^ ffffffc064d57c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffffffc064d57c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Since the shadow byte pointed by the report is 0, so it may mean it is just hit oob in non-current task. So, disable the instrumentation here.

Signed-off-by: Yang Shi yang.shi@linaro.org --- arch/arm64/kernel/stacktrace.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 4fad978..88278c2 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -20,6 +20,7 @@ #include <linux/ftrace.h> #include <linux/sched.h> #include <linux/stacktrace.h> +#include <linux/kasan.h>

#include <asm/irq.h> #include <asm/stacktrace.h> @@ -64,7 +65,9 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) return -EINVAL;

frame->sp = fp + 0x10; + kasan_disable_current(); frame->fp = *(unsigned long *)(fp); + kasan_enable_current(); frame->pc = *(unsigned long *)(fp + 8);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER