From: Eiichi Tsukata <devel@xxxxxxxxxxxx> commit 2af7c85714d8cafadf925d55441458eae312cd6b upstream. When arch_stack_walk_user() is called from atomic contexts, access_ok() can trigger the following warning if compiled with CONFIG_DEBUG_ATOMIC_SLEEP=y. Reproducer: // CONFIG_DEBUG_ATOMIC_SLEEP=y # cd /sys/kernel/debug/tracing # echo 1 > options/userstacktrace # echo 1 > events/irq/irq_handler_entry/enable WARNING: CPU: 0 PID: 2649 at arch/x86/kernel/stacktrace.c:103 arch_stack_walk_user+0x6e/0xf6 CPU: 0 PID: 2649 Comm: bash Not tainted 5.3.0-rc1+ #99 RIP: 0010:arch_stack_walk_user+0x6e/0xf6 Call Trace: <IRQ> stack_trace_save_user+0x10a/0x16d trace_buffer_unlock_commit_regs+0x185/0x240 trace_event_buffer_commit+0xec/0x330 trace_event_raw_event_irq_handler_entry+0x159/0x1e0 __handle_irq_event_percpu+0x22d/0x440 handle_irq_event_percpu+0x70/0x100 handle_irq_event+0x5a/0x8b handle_edge_irq+0x12f/0x3f0 handle_irq+0x34/0x40 do_IRQ+0xa6/0x1f0 common_interrupt+0xf/0xf </IRQ> Fix it by calling __range_not_ok() directly instead of access_ok() as copy_from_user_nmi() does. This is fine here because the actual copy is inside a pagefault disabled region. Reported-by: Juri Lelli <juri.lelli@xxxxxxxxx> Signed-off-by: Eiichi Tsukata <devel@xxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20190722083216.16192-2-devel@xxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/stacktrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -100,7 +100,7 @@ copy_stack_frame(const void __user *fp, { int ret; - if (!access_ok(fp, sizeof(*frame))) + if (__range_not_ok(fp, sizeof(*frame), TASK_SIZE)) return 0; ret = 1;
