Re: 3.0.1 compile error on Fedora 15

Ben Greear
2011-08-08T19:33:12Z

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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