2016-06-05 21:49 GMT+09:00 Dmitry Vyukov <dvyukov@google.com>:

> On Sun, Jun 5, 2016 at 1:11 PM, seokhoon.yoon <iamyooon@gmail.com> wrote:
> > When Kasan tell memory access is write or not, use true or false.
> > This expression is simple and convenient.
> >
> > But I think it is possible to more readable. and so change it.
> >
> > Signed-off-by: seokhoon.yoon <iamyooon@gmail.com>
> > ---
> >  mm/kasan/kasan.c  | 32 ++++++++++++++++----------------
> >  mm/kasan/kasan.h  | 12 ++++++++++--
> >  mm/kasan/report.c | 16 ++++++++--------
> >  3 files changed, 34 insertions(+), 26 deletions(-)
> >
> > diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> > index 18b6a2b..642d936 100644
> > --- a/mm/kasan/kasan.c
> > +++ b/mm/kasan/kasan.c
> > @@ -274,7 +274,7 @@ static __always_inline bool
> memory_is_poisoned(unsigned long addr, size_t size)
> >  }
> >
> >  static __always_inline void check_memory_region_inline(unsigned long
> addr,
> > -                                               size_t size, bool write,
> > +                                               size_t size, enum
> acc_type type,
> >                                                 unsigned long ret_ip)
> >  {
> >         if (unlikely(size == 0))
> > @@ -282,39 +282,39 @@ static __always_inline void
> check_memory_region_inline(unsigned long addr,
> >
> >         if (unlikely((void *)addr <
> >                 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
> > -               kasan_report(addr, size, write, ret_ip);
> > +               kasan_report(addr, size, type, ret_ip);
> >                 return;
> >         }
> >
> >         if (likely(!memory_is_poisoned(addr, size)))
> >                 return;
> >
> > -       kasan_report(addr, size, write, ret_ip);
> > +       kasan_report(addr, size, type, ret_ip);
> >  }
> >
> >  static void check_memory_region(unsigned long addr,
> > -                               size_t size, bool write,
> > +                               size_t size, enum acc_type type,
> >                                 unsigned long ret_ip)
> >  {
> > -       check_memory_region_inline(addr, size, write, ret_ip);
> > +       check_memory_region_inline(addr, size, type, ret_ip);
> >  }
> >
> >  void kasan_check_read(const void *p, unsigned int size)
> >  {
> > -       check_memory_region((unsigned long)p, size, false, _RET_IP_);
> > +       check_memory_region((unsigned long)p, size, READ_MODE, _RET_IP_);
> >  }
> >  EXPORT_SYMBOL(kasan_check_read);
> >
> >  void kasan_check_write(const void *p, unsigned int size)
> >  {
> > -       check_memory_region((unsigned long)p, size, true, _RET_IP_);
> > +       check_memory_region((unsigned long)p, size, WRITE_MODE,
> _RET_IP_);
> >  }
> >  EXPORT_SYMBOL(kasan_check_write);
> >
> >  #undef memset
> >  void *memset(void *addr, int c, size_t len)
> >  {
> > -       check_memory_region((unsigned long)addr, len, true, _RET_IP_);
> > +       check_memory_region((unsigned long)addr, len, WRITE_MODE,
> _RET_IP_);
> >
> >         return __memset(addr, c, len);
> >  }
> > @@ -322,8 +322,8 @@ void *memset(void *addr, int c, size_t len)
> >  #undef memmove
> >  void *memmove(void *dest, const void *src, size_t len)
> >  {
> > -       check_memory_region((unsigned long)src, len, false, _RET_IP_);
> > -       check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> > +       check_memory_region((unsigned long)src, len, READ_MODE,
> _RET_IP_);
> > +       check_memory_region((unsigned long)dest, len, WRITE_MODE,
> _RET_IP_);
> >
> >         return __memmove(dest, src, len);
> >  }
> > @@ -331,8 +331,8 @@ void *memmove(void *dest, const void *src, size_t
> len)
> >  #undef memcpy
> >  void *memcpy(void *dest, const void *src, size_t len)
> >  {
> > -       check_memory_region((unsigned long)src, len, false, _RET_IP_);
> > -       check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> > +       check_memory_region((unsigned long)src, len, READ_MODE,
> _RET_IP_);
> > +       check_memory_region((unsigned long)dest, len, WRITE_MODE,
> _RET_IP_);
> >
> >         return __memcpy(dest, src, len);
> >  }
> > @@ -709,7 +709,7 @@ EXPORT_SYMBOL(__asan_unregister_globals);
> >  #define DEFINE_ASAN_LOAD_STORE(size)                                   \
> >         void __asan_load##size(unsigned long addr)                      \
> >         {                                                               \
> > -               check_memory_region_inline(addr, size, false, _RET_IP_);\
> > +               check_memory_region_inline(addr, size, READ_MODE,
> _RET_IP_);\
> >         }                                                               \
> >         EXPORT_SYMBOL(__asan_load##size);                               \
> >         __alias(__asan_load##size)                                      \
> > @@ -717,7 +717,7 @@ EXPORT_SYMBOL(__asan_unregister_globals);
> >         EXPORT_SYMBOL(__asan_load##size##_noabort);                     \
> >         void __asan_store##size(unsigned long addr)                     \
> >         {                                                               \
> > -               check_memory_region_inline(addr, size, true, _RET_IP_); \
> > +               check_memory_region_inline(addr, size, WRITE_MODE,
> _RET_IP_);\
> >         }                                                               \
> >         EXPORT_SYMBOL(__asan_store##size);                              \
> >         __alias(__asan_store##size)                                     \
> > @@ -732,7 +732,7 @@ DEFINE_ASAN_LOAD_STORE(16);
> >
> >  void __asan_loadN(unsigned long addr, size_t size)
> >  {
> > -       check_memory_region(addr, size, false, _RET_IP_);
> > +       check_memory_region(addr, size, READ_MODE, _RET_IP_);
> >  }
> >  EXPORT_SYMBOL(__asan_loadN);
> >
> > @@ -742,7 +742,7 @@ EXPORT_SYMBOL(__asan_loadN_noabort);
> >
> >  void __asan_storeN(unsigned long addr, size_t size)
> >  {
> > -       check_memory_region(addr, size, true, _RET_IP_);
> > +       check_memory_region(addr, size, WRITE_MODE, _RET_IP_);
> >  }
> >  EXPORT_SYMBOL(__asan_storeN);
> >
> > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> > index 7f7ac51..47cb58c 100644
> > --- a/mm/kasan/kasan.h
> > +++ b/mm/kasan/kasan.h
> > @@ -27,11 +27,19 @@
> >  #define KASAN_ABI_VERSION 1
> >  #endif
> >
> > +/*
> > + * Distinguish memory access
> > + */
> > +enum acc_type {
> > +       READ_MODE,
> > +       WRITE_MODE
> > +};
> > +
> >  struct kasan_access_info {
> >         const void *access_addr;
> >         const void *first_bad_addr;
> >         size_t access_size;
> > -       bool is_write;
> > +       enum acc_type access_type;
> >         unsigned long ip;
> >  };
> >
> > @@ -109,7 +117,7 @@ static inline bool kasan_report_enabled(void)
> >  }
> >
> >  void kasan_report(unsigned long addr, size_t size,
> > -               bool is_write, unsigned long ip);
> > +               enum acc_type type, unsigned long ip);
> >
> >  #ifdef CONFIG_SLAB
> >  void quarantine_put(struct kasan_free_meta *info, struct kmem_cache
> *cache);
> > diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> > index b3c122d..e0bee22 100644
> > --- a/mm/kasan/report.c
> > +++ b/mm/kasan/report.c
> > @@ -96,7 +96,7 @@ static void print_error_description(struct
> kasan_access_info *info)
> >                 bug_type, (void *)info->ip,
> >                 info->access_addr);
> >         pr_err("%s of size %zu by task %s/%d\n",
> > -               info->is_write ? "Write" : "Read",
> > +               info->access_type == WRITE_MODE ? "Write" : "Read",
> >                 info->access_size, current->comm, task_pid_nr(current));
> >  }
> >
> > @@ -267,7 +267,7 @@ static void kasan_report_error(struct
> kasan_access_info *info)
> >                 pr_err("BUG: KASAN: %s on address %p\n",
> >                         bug_type, info->access_addr);
> >                 pr_err("%s of size %zu by task %s/%d\n",
> > -                       info->is_write ? "Write" : "Read",
> > +                       info->access_type == WRITE_MODE ? "Write" :
> "Read",
> >                         info->access_size, current->comm,
> >                         task_pid_nr(current));
> >                 dump_stack();
> > @@ -283,7 +283,7 @@ static void kasan_report_error(struct
> kasan_access_info *info)
> >  }
> >
> >  void kasan_report(unsigned long addr, size_t size,
> > -               bool is_write, unsigned long ip)
> > +               enum acc_type type, unsigned long ip)
> >  {
> >         struct kasan_access_info info;
> >
> > @@ -292,7 +292,7 @@ void kasan_report(unsigned long addr, size_t size,
> >
> >         info.access_addr = (void *)addr;
> >         info.access_size = size;
> > -       info.is_write = is_write;
> > +       info.access_type = type;
> >         info.ip = ip;
> >
> >         kasan_report_error(&info);
> > @@ -302,14 +302,14 @@ void kasan_report(unsigned long addr, size_t size,
> >  #define DEFINE_ASAN_REPORT_LOAD(size)                     \
> >  void __asan_report_load##size##_noabort(unsigned long addr) \
> >  {                                                         \
> > -       kasan_report(addr, size, false, _RET_IP_);        \
> > +       kasan_report(addr, size, READ_MODE, _RET_IP_);    \
> >  }                                                         \
> >  EXPORT_SYMBOL(__asan_report_load##size##_noabort)
> >
> >  #define DEFINE_ASAN_REPORT_STORE(size)                     \
> >  void __asan_report_store##size##_noabort(unsigned long addr) \
> >  {                                                          \
> > -       kasan_report(addr, size, true, _RET_IP_);          \
> > +       kasan_report(addr, size, WRITE_MODE, _RET_IP_);    \
> >  }                                                          \
> >  EXPORT_SYMBOL(__asan_report_store##size##_noabort)
> >
> > @@ -326,12 +326,12 @@ DEFINE_ASAN_REPORT_STORE(16);
> >
> >  void __asan_report_load_n_noabort(unsigned long addr, size_t size)
> >  {
> > -       kasan_report(addr, size, false, _RET_IP_);
> > +       kasan_report(addr, size, READ_MODE, _RET_IP_);
> >  }
> >  EXPORT_SYMBOL(__asan_report_load_n_noabort);
> >
> >  void __asan_report_store_n_noabort(unsigned long addr, size_t size)
> >  {
> > -       kasan_report(addr, size, true, _RET_IP_);
> > +       kasan_report(addr, size, WRITE_MODE, _RET_IP_);
> >  }
> >  EXPORT_SYMBOL(__asan_report_store_n_noabort);
>
>
> Hello seokhoon.yoon,
>
> Hi Dmitry,
thanks for your replies.


>
> Where exactly do you hit readability problems?
>

I don`t hit readablity problem,but kasan need to abstract this expression.
I think more abstraction give us more readablity. isn't it? :)


> I would say that the only problematic place is where we initialize the
> value:
>
>     kasan_report(addr, size, true, _RET_IP_);
>     check_memory_region(addr, size, true, _RET_IP_);
>
Here it is really difficult to say what true/false mean. Even if you
> know that it is access type, you don't necessary remember if true

means write or read. That could be solved by adding comments:
>
>     kasan_report(addr, size, /* write = */ true, _RET_IP_);
>
> In all other places one sees that we are talking about "write".


thanks.