Messages in this thread | | | Date | Wed, 31 Mar 2021 17:49:08 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] ia64: fix user_stack_pointer() for ptrace() |
| |
On Wed, 31 Mar 2021 09:44:47 +0100 Sergei Trofimovich <slyfox@gentoo.org> 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.
| |