Re: 3.0.1 compile error on Fedora 15

[Randy Dunlap <rdunlap@xenotime.net>]

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):


---
 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