mm: madvise(): correct return code

The posix_madvise() function succeeds (and does nothing) when called with
parameters (NULL, 0, -1); according to LSB tests, it should fail with
EINVAL because -1 is not a valid flag.

When called with a valid address and size, it correctly fails.

So perform an initial check for valid flags first.

Reported-by: Jiri Dluhos <jdluhos@novell.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Reviewed-and-Tested-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 1 deletions

diff --git a/mm/madvise.c b/mm/madvise.c
index e994dcb479d6..76eb4193acdd 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -238,12 +238,30 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
                 break;
 
         default:
-                error = -EINVAL;
+                BUG();
                 break;
         }
         return error;
 }
 
+static int
+madvise_behavior_valid(int behavior)
+{
+        switch (behavior) {
+        case MADV_DOFORK:
+        case MADV_DONTFORK:
+        case MADV_NORMAL:
+        case MADV_SEQUENTIAL:
+        case MADV_RANDOM:
+        case MADV_REMOVE:
+        case MADV_WILLNEED:
+        case MADV_DONTNEED:
+                return 1;
+
+        default:
+                return 0;
+        }
+}
 /*
  * The madvise(2) system call.
  *
@@ -289,6 +307,9 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
         int write;
         size_t len;
 
+        if (!madvise_behavior_valid(behavior))
+                return error;
+
         write = madvise_need_mmap_write(behavior);
         if (write)
                 down_write(&current->mm->mmap_sem);