path: root/mm/mempolicy.c
diff options
authorKAMEZAWA Hiroyuki <>2011-09-14 16:21:02 -0700
committerLinus Torvalds <>2011-09-14 18:09:36 -0700
commit2bbff6c761e31b4642d297513cd3e0e89bc68ff7 (patch)
tree4555f0e22d503e04d5b1ff103096d6bd517a2422 /mm/mempolicy.c
parent8aacc9f550feb09c8b26470498345c192996a68e (diff)
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 <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/mempolicy.c')
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);