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| author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2011-09-14 16:21:02 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-09-14 18:09:36 -0700 |
| commit | 2bbff6c761e31b4642d297513cd3e0e89bc68ff7 (patch) | |
| tree | 4555f0e22d503e04d5b1ff103096d6bd517a2422 /mm/mempolicy.c | |
| parent | 8aacc9f550feb09c8b26470498345c192996a68e (diff) | |
| download | lwn-2bbff6c761e31b4642d297513cd3e0e89bc68ff7.tar.gz lwn-2bbff6c761e31b4642d297513cd3e0e89bc68ff7.zip | |
mm/mempolicy.c: make copy_from_user() provably correct
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>
Diffstat (limited to 'mm/mempolicy.c')
| -rw-r--r-- | mm/mempolicy.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index b1f70d6eec35..9c51f9f58cac 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -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); |