Re: [PATCH v1 1/2] Missing instruction_pointer_set() instances

[Jin, Yao]

Hi Peter,

On 8/4/2020 7:31 PM, peterz@xxxxxxxxxxxxx wrote:
> On Fri, Jul 31, 2020 at 10:56:16AM +0800, Jin Yao wrote:
> > There is a potential security issue that perf kernel samples
> > may be leaked even though kernel sampling is disabled. For fixing
> > the potential leakage, the idea is to use instruction_pointer_set
> > to set invalid ip address in leaked perf samples in some cases.
> >
> > But instruction_pointer_set is missing on some architectures.
> > Define instruction_pointer_set for these architectures.
> >
> > Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
> > ---
> >   arch/alpha/include/asm/ptrace.h  | 6 ++++++
> >   arch/arc/include/asm/ptrace.h    | 6 ++++++
> >   arch/nds32/include/asm/ptrace.h  | 7 +++++++
> >   arch/xtensa/include/asm/ptrace.h | 6 ++++++
> >   4 files changed, 25 insertions(+)
>
> AFAICT you forgot to actually Cc the maintainers for all that.

Thanks so much for helping to Cc the maintainers. I just checked the MAINTAINERS file and Cc the 
maintainer for PTRACE SUPPORT but I forgot to use the get_maintainer.pl script. :(

Thanks
Jin Yao

> > diff --git a/arch/alpha/include/asm/ptrace.h b/arch/alpha/include/asm/ptrace.h
> > index df5f317ab3fc..c464d525c110 100644
> > --- a/arch/alpha/include/asm/ptrace.h
> > +++ b/arch/alpha/include/asm/ptrace.h
> > @@ -25,4 +25,10 @@ static inline unsigned long regs_return_value(struct pt_regs *regs)
> >   	return regs->r0;
> >   }
> >   
> > +static inline void instruction_pointer_set(struct pt_regs *regs,
> > +					   unsigned long val)
> > +{
> > +	regs->pc = val;
> > +}
> > +
> >   #endif
> > diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
> > index 2fdb87addadc..8869a6c0fe8c 100644
> > --- a/arch/arc/include/asm/ptrace.h
> > +++ b/arch/arc/include/asm/ptrace.h
> > @@ -154,6 +154,12 @@ static inline long regs_return_value(struct pt_regs *regs)
> >   	return (long)regs->r0;
> >   }
> >   
> > +static inline void instruction_pointer_set(struct pt_regs *regs,
> > +					   unsigned long val)
> > +{
> > +	regs->ret = val;
> > +}
> > +
> >   #endif /* !__ASSEMBLY__ */
> >   
> >   #endif /* __ASM_PTRACE_H */
> > diff --git a/arch/nds32/include/asm/ptrace.h b/arch/nds32/include/asm/ptrace.h
> > index 919ee223620c..19a916bef7f5 100644
> > --- a/arch/nds32/include/asm/ptrace.h
> > +++ b/arch/nds32/include/asm/ptrace.h
> > @@ -62,6 +62,13 @@ static inline unsigned long regs_return_value(struct pt_regs *regs)
> >   {
> >   	return regs->uregs[0];
> >   }
> > +
> > +static inline void instruction_pointer_set(struct pt_regs *regs,
> > +					   unsigned long val)
> > +{
> > +	regs->ipc = val;
> > +}
> > +
> >   extern void show_regs(struct pt_regs *);
> >   /* Avoid circular header include via sched.h */
> >   struct task_struct;
> > diff --git a/arch/xtensa/include/asm/ptrace.h b/arch/xtensa/include/asm/ptrace.h
> > index b109416dc07e..82ab1ba99259 100644
> > --- a/arch/xtensa/include/asm/ptrace.h
> > +++ b/arch/xtensa/include/asm/ptrace.h
> > @@ -90,6 +90,12 @@ struct pt_regs {
> >   # define return_pointer(regs) (MAKE_PC_FROM_RA((regs)->areg[0], \
> >   					       (regs)->areg[1]))
> >   
> > +static inline void instruction_pointer_set(struct pt_regs *regs,
> > +					   unsigned long val)
> > +{
> > +	regs->pc = val;
> > +}
> > +
> >   # ifndef CONFIG_SMP
> >   #  define profile_pc(regs) instruction_pointer(regs)
> >   # else
> > --
> > 2.17.1