[PATCH] Fix MADV_REMOVE protection checking

madvise_remove needs to respect file and mmap protections.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
[ Will the real CVE-2006-1524 stand up, please.. ]
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/madvise.c b/mm/madvise.c
index af3d573..4e19615 100644 (file)
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -168,6 +168,9 @@ static long madvise_remove(struct vm_area_struct *vma,
                        return -EINVAL;
        }
 
+       if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
+               return -EACCES;
+
        mapping = vma->vm_file->f_mapping;
 
        offset = (loff_t)(start - vma->vm_start)