mbox series

[0/2] Fix truncation warnings from building test_scanf.c

Message ID 20210524155941.16376-1-rf@opensource.cirrus.com
Headers show
Series Fix truncation warnings from building test_scanf.c | expand

Message

Richard Fitzgerald May 24, 2021, 3:59 p.m. UTC 
The kernel test robot is reporting truncation warnings when building
lib/test_scanf.c:

1) lib/test_scanf.c:250:9: sparse: sparse: cast truncates bits from
   constant value (ffff0001 becomes 1)
   Reported on several lines.

2) include/linux/prandom.h:114:45: sparse: sparse: cast truncates bits
   from constant value (4f2e5357408c3c09 becomes 408c3c09)


(1) is caused by test_scanf.c using type_min() on an unsigned type. The
type_min() macro calculates -type_max() - 1, so is only meaningful for
signed types.

(2) is caused by prandom_seed_state() storing a modified u64 seed value
into a u32 - sparse will warn that this causes a truncation. 

The two patches in this series fix these problems.

Richard Fitzgerald (2):
  lib: test_scanf: Fix incorrect use of type_min() with unsigned types
  random32: Fix implicit truncation warning in prandom_seed_state()

 include/linux/prandom.h |  2 +-
 lib/test_scanf.c        | 13 ++++++-------
 2 files changed, 7 insertions(+), 8 deletions(-)

Comments

Petr Mladek May 25, 2021, 9:20 a.m. UTC | #1 
On Mon 2021-05-24 16:59:39, Richard Fitzgerald wrote:
> The kernel test robot is reporting truncation warnings when building

> lib/test_scanf.c:

> 

> Richard Fitzgerald (2):

>   lib: test_scanf: Fix incorrect use of type_min() with unsigned types

>   random32: Fix implicit truncation warning in prandom_seed_state()

> 

>  include/linux/prandom.h |  2 +-

>  lib/test_scanf.c        | 13 ++++++-------

>  2 files changed, 7 insertions(+), 8 deletions(-)


For both patches:

Reviewed-by: Petr Mladek <pmladek@suse.com>


I am going to commit them within next two days or so unless anyone
complains in the meantime.

Thanks a lot for fixing it.

Best Regards,
Petr
Petr Mladek May 27, 2021, 2:10 p.m. UTC | #2 
On Tue 2021-05-25 11:20:45, Petr Mladek wrote:
> On Mon 2021-05-24 16:59:39, Richard Fitzgerald wrote:

> > The kernel test robot is reporting truncation warnings when building

> > lib/test_scanf.c:

> > 

> > Richard Fitzgerald (2):

> >   lib: test_scanf: Fix incorrect use of type_min() with unsigned types

> >   random32: Fix implicit truncation warning in prandom_seed_state()

> > 

> >  include/linux/prandom.h |  2 +-

> >  lib/test_scanf.c        | 13 ++++++-------

> >  2 files changed, 7 insertions(+), 8 deletions(-)

> 

> For both patches:

> 

> Reviewed-by: Petr Mladek <pmladek@suse.com>

> 

> I am going to commit them within next two days or so unless anyone

> complains in the meantime.


JFYI, both patches have been committed into  printk/linux.git,
branch for-5.14-vsprintf-scanf.

Best Regards,
Petr