From 3428030da004a1128cbdcf93dc03e16f184d845b Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Tue, 22 Jan 2019 07:01:39 +0200 Subject: ovl: fix missing upper fs freeze protection on copy up for ioctl Generalize the helper ovl_open_maybe_copy_up() and use it to copy up file with data before FS_IOC_SETFLAGS ioctl. The FS_IOC_SETFLAGS ioctl is a bit of an odd ball in vfs, which probably caused the confusion. File may be open O_RDONLY, but ioctl modifies the file. VFS does not call mnt_want_write_file() nor lock inode mutex, but fs-specific code for FS_IOC_SETFLAGS does. So ovl_ioctl() calls mnt_want_write_file() for the overlay file, and fs-specific code calls mnt_want_write_file() for upper fs file, but there was no call for ovl_want_write() for copy up duration which prevents overlayfs from copying up on a frozen upper fs. Fixes: dab5ca8fd9dd ("ovl: add lsattr/chattr support") Cc: # v4.19 Signed-off-by: Amir Goldstein Acked-by: Vivek Goyal Signed-off-by: Miklos Szeredi --- fs/overlayfs/file.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'fs/overlayfs/file.c') diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 84dd957efa24..50e4407398d8 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -116,11 +116,10 @@ static int ovl_real_fdget(const struct file *file, struct fd *real) static int ovl_open(struct inode *inode, struct file *file) { - struct dentry *dentry = file_dentry(file); struct file *realfile; int err; - err = ovl_open_maybe_copy_up(dentry, file->f_flags); + err = ovl_maybe_copy_up(file_dentry(file), file->f_flags); if (err) return err; @@ -390,7 +389,7 @@ static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg) if (ret) return ret; - ret = ovl_copy_up_with_data(file_dentry(file)); + ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY); if (!ret) { ret = ovl_real_ioctl(file, cmd, arg); -- cgit v1.2.3