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

peterz
2020-08-04T11:32:06Z

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@linux.intel.com>
> ---
> 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.

> 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
>