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

Jin, Yao
2020-08-05T00:26:07Z

Hi Peter,

On 8/4/2020 7:31 PM, peterz@infradead.org 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@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.
>

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
>>