[PATCH] msync: fix return value

msync() does a strange thing.  Essentially:

	vma = find_vma();
	for ( ; ; ) {
		if (!vma)
			return -ENOMEM;
		...
		vma = vma->vm_next;
	}

so an msync() request which starts within or before a valid VMA and which ends
within or beyond the final VMA will incorrectly return -ENOMEM.

Fix.

Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 7 deletions

diff --git a/mm/msync.c b/mm/msync.c
index ee9bd6759833..d6a50f3f28b6 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -146,7 +146,8 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
 {
         unsigned long end;
         struct vm_area_struct *vma;
-        int unmapped_error, error = -EINVAL;
+        int unmapped_error = 0;
+        int error = -EINVAL;
         int done = 0;
 
         if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
@@ -171,15 +172,14 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
         if (flags & MS_SYNC)
                 current->flags |= PF_SYNCWRITE;
         vma = find_vma(current->mm, start);
-        unmapped_error = 0;
+        if (!vma) {
+                error = -ENOMEM;
+                goto out_unlock;
+        }
         do {
                 unsigned long nr_pages_dirtied = 0;
                 struct file *file;
 
-                /* Still start < end. */
-                error = -ENOMEM;
-                if (!vma)
-                        goto out_unlock;
                 /* Here start < vma->vm_end. */
                 if (start < vma->vm_start) {
                         unmapped_error = -ENOMEM;
@@ -239,7 +239,7 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
                 } else {
                         vma = vma->vm_next;
                 }
-        } while (!done);
+        } while (vma && !done);
 out_unlock:
         current->flags &= ~PF_SYNCWRITE;
         up_read(&current->mm->mmap_sem);