Re: [PATCH] vsprintf: sanely handle NULL passed to %pe
From: Rasmus Villemoes
Date: Wed Feb 19 2020 - 08:56:37 EST
On 19/02/2020 14.48, Petr Mladek wrote:
> On Wed 2020-02-19 12:53:22, Rasmus Villemoes wrote:
>> --- a/lib/vsprintf.c
>> +++ b/lib/vsprintf.c
>> @@ -619,7 +619,7 @@ static char *err_ptr(char *buf, char *end, void *ptr,
>> struct printf_spec spec)
>> int err = PTR_ERR(ptr);
>> - const char *sym = errname(err);
>> + const char *sym = err ? errname(err) : "NULL";
> I like this more than adding "NULL" errname.
>> if (sym)
>> return string_nocheck(buf, end, sym, spec);
>> instead of the change(s) in errname.c? And then the test case for
>> '"%pe", NULL' should also be moved outside CONFIG_SYMBOLIC_ERRNAME.
> The test should go into null_pointer() instead of errptr().
Eh, no, the behaviour of %pe is tested by errptr(). I'll keep it that
way. But I should add a #else section that tests how %pe behaves without
CONFIG_SYMBOLIC_ERRNAME - though that's orthogonal to this patch.
> Could you send updated patch, please? ;-)
I'll wait a day or two for more comments. It doesn't seem very urgent.
>> BTW., your original patch for %p lacks corresponding update of
>> test_vsprintf.c. Please add appropriate test cases.
> Good point. The existing test_hashed() is rather weak
> and it did not catch this change.
> It would be nice to make test_hash() more powerful.
> Anyway, the minimal udpate would be:
> diff --git a/lib/test_printf.c b/lib/test_printf.c
> index 2d9f520d2f27..1726a678bccd 100644
> --- a/lib/test_printf.c
> +++ b/lib/test_printf.c
> @@ -333,7 +333,7 @@ test_hashed(const char *fmt, const void *p)
> static void __init
> - test_hashed("%p", NULL);
> + test(ZEROS "00000000", "%p", NULL);
No, it most certainly also needs to check a few "%p", ERR_PTR(-4) cases
(where one of course has to use explicit integers and not E* constants).