Re: 3.0.1 compile error on Fedora 15

[Ben Greear <greearb@candelatech.com>]

On 08/08/2011 12:11 PM, Randy Dunlap wrote:
> On Mon, 08 Aug 2011 11:55:29 -0700 Ben Greear wrote:
>
>> On 08/08/2011 11:52 AM, Randy Dunlap wrote:
>>> On Mon, 08 Aug 2011 11:43:43 -0700 Ben Greear wrote:
>>>
>>>> [greearb@t60-ben linux-3.0.p4s]$ make
>>>> make -C /home/greearb/git/linux-3.0.dev.y O=/home/greearb/kernel/2.6/linux-3.0.p4s/.
>>>>      Using /home/greearb/git/linux-3.0.dev.y as source for kernel
>>>>      GEN     /home/greearb/kernel/2.6/linux-3.0.p4s/Makefile
>>>>      CHK     include/linux/version.h
>>>>      CHK     include/generated/utsrelease.h
>>>>      CALL    /home/greearb/git/linux-3.0.dev.y/scripts/checksyscalls.sh
>>>>      CHK     include/generated/compile.h
>>>>      CC      fs/binfmt_misc.o
>>>> In file included from /home/greearb/git/linux-3.0.dev.y/arch/x86/include/asm/uaccess.h:570:0,
>>>>                     from /home/greearb/git/linux-3.0.dev.y/include/linux/uaccess.h:5,
>>>>                     from /home/greearb/git/linux-3.0.dev.y/include/linux/highmem.h:7,
>>>>                     from /home/greearb/git/linux-3.0.dev.y/include/linux/pagemap.h:10,
>>>>                     from /home/greearb/git/linux-3.0.dev.y/fs/binfmt_misc.c:26:
>>>> /home/greearb/git/linux-3.0.dev.y/arch/x86/include/asm/uaccess_32.h: In function ‘parse_command.part.0’:
>>>> /home/greearb/git/linux-3.0.dev.y/arch/x86/include/asm/uaccess_32.h:211:26: error: call to ‘copy_from_user_overflow’ declared with attribute error:
>>>> copy_from_user() buffer size is not provably correct
>>>> make[3]: *** [fs/binfmt_misc.o] Error 1
>>>> make[2]: *** [fs] Error 2
>>>> make[1]: *** [sub-make] Error 2
>>>> make: *** [all] Error 2
>>>> [greearb@t60-ben linux-3.0.p4s]$
>>>>
>>>>
>>>> The code in question is below.  Is this missing an assignment to n
>>>> in the else branch?
>>>>
>>>> static inline unsigned long __must_check copy_from_user(void *to,
>>>>                                              const void __user *from,
>>>>                                              unsigned long n)
>>>> {
>>>>            int sz = __compiletime_object_size(to);
>>>>
>>>>            if (likely(sz == -1 || sz>= n))
>>>>                    n = _copy_from_user(to, from, n);
>>>>            else
>>>>                    copy_from_user_overflow();
>>>>
>>>>            return n;
>>>> }
>>>
>>>
>>> Do you have this kconfig option enabled?
>>> CONFIG_DEBUG_STRICT_USER_COPY_CHECKS=y
>>>
>>> If so, you should get the error that you reported.
>>> If not, then you need a patch like the one below (which has been posted
>>> by other people several times -- might need to be added to -stable):
>>
>> I do have that enabled.   I'm slightly confused by your response above:
>>
>> Do I need to disable the check AND apply the patch below, or just disable
>> the check, or just apply the patch and leave the check enabled?
>
> Hm, I guess I'm confused also.  The patch only applies to linux-next,
> not to 3.0.x.
>
> The patch below is needed (in linux-next) to fix a build
> error when CONFIG_DEBUG_STRICT_USER_COPY_CHECKS is not enabled.
>
> When you do have CONFIG_DEBUG_STRICT_USER_COPY_CHECKS, the build error is
> the correct result.  AFAIK.  So it looks to me like you should either
> disable the kconfig option or fix the code in fs/binfmt_misc.c.
> I would do the former -- depending on your use case.

I can disable the check, but I hope someone fixes the real problem
and sends the patch to stable.  Seems a bit lame that we have compile
errors in stable series...

Thanks,
Ben

>
>
>> Thanks,
>> Ben
>>
>>>
>>>
>>> ---
>>>    lib/Makefile |    2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> --- linux-next-20110728.orig/lib/Makefile
>>> +++ linux-next-20110728/lib/Makefile
>>> @@ -14,7 +14,7 @@ lib-y := ctype.o string.o vsprintf.o cmd
>>>    	 proportions.o prio_heap.o ratelimit.o show_mem.o \
>>>    	 is_single_threaded.o plist.o decompress.o find_next_bit.o
>>>
>>> -lib-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
>>> +obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
>>>    lib-$(CONFIG_MMU) += ioremap.o
>>>    lib-$(CONFIG_SMP) += cpumask.o
>>>
>>
>>
>> --
>
>
> ---
> ~Randy
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
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-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com