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mm/mempolicy.c: make copy_from_user() provably correct

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When compiling mm/mempolicy.c with struct user copy checks the following
warning is shown:

  In file included from arch/x86/include/asm/uaccess.h:572,
                   from include/linux/uaccess.h:5,
                   from include/linux/highmem.h:7,
                   from include/linux/pagemap.h:10,
                   from include/linux/mempolicy.h:70,
                   from mm/mempolicy.c:68:
  In function `copy_from_user',
      inlined from `compat_sys_get_mempolicy' at mm/mempolicy.c:1415:
  arch/x86/include/asm/uaccess_64.h:64: warning: call to `copy_from_user_overflow' declared with attribute warning: copy_from_user() buffer size is not provably correct
    LD      mm/built-in.o

Fix this by passing correct buffer size value.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KAMEZAWA Hiroyuki 2011-09-14 16:21:02 -07:00 committed by Linus Torvalds
parent 8aacc9f550
commit 2bbff6c761
1 changed files with 3 additions and 1 deletions
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4
mm/mempolicy.c
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@ -1411,7 +1411,9 @@ asmlinkage long compat_sys_get_mempolicy(int __user *policy,
err = sys_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
if (!err && nmask) {
err = copy_from_user(bm, nm, alloc_size);
unsigned long copy_size;
copy_size = min_t(unsigned long, sizeof(bm), alloc_size);
err = copy_from_user(bm, nm, copy_size);
/* ensure entire bitmap is zeroed */
err |= clear_user(nmask, ALIGN(maxnode-1, 8) / 8);
err |= compat_put_bitmap(nmask, bm, nr_bits);