On Wed, 31 Mar 2021 17:49:08 -0700 Andrew Morton <[email protected]> wrote:
> On Wed, 31 Mar 2021 09:44:47 +0100 Sergei Trofimovich <[email protected]> > wrote: > > > ia64 has two stacks: > > - memory stack (or stack), pointed at by by r12 > > - register backing store (register stack), pointed at > > ar.bsp/ar.bspstore with complications around dirty > > register frame on CPU. > > > > In https://bugs.gentoo.org/769614 Dmitry noticed that > > PTRACE_GET_SYSCALL_INFO returns register stack instead > > memory stack. > > > > The bug comes from the fact that user_stack_pointer() and > > current_user_stack_pointer() don't return the same register: > > > > ulong user_stack_pointer(struct pt_regs *regs) { return > > regs->ar_bspstore; } > > #define current_user_stack_pointer() (current_pt_regs()->r12) > > > > The change gets both back in sync. > > > > I think ptrace(PTRACE_GET_SYSCALL_INFO) is the only affected user > > by this bug on ia64. > > > > The change fixes 'rt_sigreturn.gen.test' strace test where > > it was observed initially. > > > > I assume a cc:stable is justified here? > > The bug seems to have been there for 10+ years, so there isn't a lot of > point in looking for the Fixes: reference. Yes, I think cc:stable is fine. -- Sergei
