The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 1dc1eed46f9fa4cb8a07baa24fb44c96d6dd35c9 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Date: Mon, 27 Sep 2021 11:23:57 +0200
Subject: [PATCH] ovl: fix IOCB_DIRECT if underlying fs doesn't support direct
IO
Normally the check at open time suffices, but e.g loop device does set
IOCB_DIRECT after doing its own checks (which are not sufficent for
overlayfs).
Make sure we don't call the underlying filesystem read/write method with
the IOCB_DIRECT if it's not supported.
Reported-by: Huang Jianan <huangjianan@xxxxxxxx>
Fixes: 16914e6fc7e1 ("ovl: add ovl_read_iter()")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.19
Tested-by: Huang Jianan <huangjianan@xxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index d081faa55e83..c88ac571593d 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -296,6 +296,12 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
if (ret)
return ret;
+ ret = -EINVAL;
+ if (iocb->ki_flags & IOCB_DIRECT &&
+ (!real.file->f_mapping->a_ops ||
+ !real.file->f_mapping->a_ops->direct_IO))
+ goto out_fdput;
+
old_cred = ovl_override_creds(file_inode(file)->i_sb);
if (is_sync_kiocb(iocb)) {
ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
@@ -320,7 +326,7 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
out:
revert_creds(old_cred);
ovl_file_accessed(file);
-
+out_fdput:
fdput(real);
return ret;
@@ -349,6 +355,12 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
if (ret)
goto out_unlock;
+ ret = -EINVAL;
+ if (iocb->ki_flags & IOCB_DIRECT &&
+ (!real.file->f_mapping->a_ops ||
+ !real.file->f_mapping->a_ops->direct_IO))
+ goto out_fdput;
+
if (!ovl_should_sync(OVL_FS(inode->i_sb)))
ifl &= ~(IOCB_DSYNC | IOCB_SYNC);
@@ -384,6 +396,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
}
out:
revert_creds(old_cred);
+out_fdput:
fdput(real);
out_unlock:
