From: Miklos Szeredi <miklos@xxxxxxxxxx>
This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit cf9a6784f7c1b5ee2b9159a1246e327c331c5697 ]
Without this copy-up of a file can be forced, even without actually being
allowed to do anything on the file.
[Arnd Bergmann] include <linux/pagemap.h> for PAGE_CACHE_SIZE (used by
MAX_LFS_FILESIZE definition).
Signed-off-by: Miklos Szeredi <miklos@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
fs/overlayfs/inode.c | 13 +++++++++++++
fs/overlayfs/super.c | 2 ++
2 files changed, 15 insertions(+)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index ba0db26..a1b069e 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -45,6 +45,19 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
int err;
struct dentry *upperdentry;
+ /*
+ * Check for permissions before trying to copy-up. This is redundant
+ * since it will be rechecked later by ->setattr() on upper dentry. But
+ * without this, copy-up can be triggered by just about anybody.
+ *
+ * We don't initialize inode->size, which just means that
+ * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
+ * check for a swapfile (which this won't be anyway).
+ */
+ err = inode_change_ok(dentry->d_inode, attr);
+ if (err)
+ return err;
+
err = ovl_want_write(dentry);
if (err)
goto out;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index c4b595e..bd6d5c1 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -9,6 +9,7 @@
#include <linux/fs.h>
#include <linux/namei.h>
+#include <linux/pagemap.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include <linux/mount.h>
@@ -847,6 +848,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
}
sb->s_stack_depth = 0;
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
if (ufs->config.upperdir) {
if (!ufs->config.workdir) {
pr_err("overlayfs: missing 'workdir'\n");
--
2.5.0
--
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