Merge "Merge android-4.4.181 (bd858d7) into msm-4.4"

1 files changed, 22 insertions, 1 deletions

diff --git a/mm/mincore.c b/mm/mincore.c
index 14bb9fb37f0c..9700c2303941 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -165,6 +165,22 @@ out:
 	return 0;
 }
 
+static inline bool can_do_mincore(struct vm_area_struct *vma)
+{
+	if (vma_is_anonymous(vma))
+		return true;
+	if (!vma->vm_file)
+		return false;
+	/*
+	 * Reveal pagecache information only for non-anonymous mappings that
+	 * correspond to the files the calling process could (if tried) open
+	 * for writing; otherwise we'd be including shared non-exclusive
+	 * mappings, which opens a side channel.
+	 */
+	return inode_owner_or_capable(file_inode(vma->vm_file)) ||
+		inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
+}
+
 /*
  * Do a chunk of "sys_mincore()". We've already checked
  * all the arguments, we hold the mmap semaphore: we should
@@ -185,8 +201,13 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v
 	vma = find_vma(current->mm, addr);
 	if (!vma || addr < vma->vm_start)
 		return -ENOMEM;
-	mincore_walk.mm = vma->vm_mm;
 	end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
+	if (!can_do_mincore(vma)) {
+		unsigned long pages = DIV_ROUND_UP(end - addr, PAGE_SIZE);
+		memset(vec, 1, pages);
+		return pages;
+	}
+	mincore_walk.mm = vma->vm_mm;
 	err = walk_page_range(addr, end, &mincore_walk);
 	if (err < 0)
 		return err;