Re: [PATCH 2/3] m68k: update ->thread.esp0 before calling syscall_trace() in ret_from_signal

Michael Schmitz
2021-09-15T22:19:37Z

Hi Al,

On 26/07/21 5:19 am, Al Viro wrote:
> We get there when sigreturn has performed obscene acts on kernel stack;
> in particular, the location of pt_regs has shifted. We are about to call
> syscall_trace(), which might stop for tracer. If that happens, we'd better
> have task_pt_regs() returning correct result...
>
> Fucked-up-by: Al Viro <viro@zeniv.linux.org.uk>
> Fixes: bd6f56a75bb2 ("m68k: Missing syscall_trace() on sigreturn")
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Looking good also, and should go to -stable.

Tested-by: Michael Schmitz <schmitzmic@gmail.com>

Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>

> ---
> arch/m68k/kernel/entry.S | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S
> index 9dd76fbb7c6b..ff9e842cec0f 100644
> --- a/arch/m68k/kernel/entry.S
> +++ b/arch/m68k/kernel/entry.S
> @@ -186,6 +186,8 @@ ENTRY(ret_from_signal)
> movel %curptr@(TASK_STACK),%a1
> tstb %a1@(TINFO_FLAGS+2)
> jge 1f
> + lea %sp@(SWITCH_STACK_SIZE),%a1
> + movel %a1,%curptr@(TASK_THREAD+THREAD_ESP0)
> jbsr syscall_trace
> 1: RESTORE_SWITCH_STACK
> addql #4,%sp