The patch below does not apply to the 4.19-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@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From acb383f1dcb4f1e79b66d4be3a0b6f519a957b0d Mon Sep 17 00:00:00 2001

From: Gao Xiang gaoxiang25@huawei.com Date: Sun, 18 Aug 2019 20:54:57 +0800 Subject: [PATCH] staging: erofs: fix an error handling in erofs_readdir()

Richard observed a forever loop of erofs_read_raw_page() [1] which can be generated by forcely setting ->u.i_blkaddr to 0xdeadbeef (as my understanding block layer can handle access beyond end of device correctly).

After digging into that, it seems the problem is highly related with directories and then I found the root cause is an improper error handling in erofs_readdir().

Let's fix it now.

[1] https://lore.kernel.org/r/1163995781.68824.1566084358245.JavaMail.zimbra@nod...

Reported-by: Richard Weinberger richard@nod.at Fixes: 3aa8ec716e52 ("staging: erofs: add directory operations") Cc: stable@vger.kernel.org # 4.19+ Reviewed-by: Chao Yu yuchao0@huawei.com Signed-off-by: Gao Xiang gaoxiang25@huawei.com Link: https://lore.kernel.org/r/20190818125457.25906-1-hsiangkao@aol.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

diff --git a/drivers/staging/erofs/dir.c b/drivers/staging/erofs/dir.c index 5f38382637e6..77ef856df9f3 100644 --- a/drivers/staging/erofs/dir.c +++ b/drivers/staging/erofs/dir.c @@ -82,8 +82,15 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx) unsigned int nameoff, maxsize;

dentry_page = read_mapping_page(mapping, i, NULL); - if (IS_ERR(dentry_page)) - continue; + if (dentry_page == ERR_PTR(-ENOMEM)) { + err = -ENOMEM; + break; + } else if (IS_ERR(dentry_page)) { + errln("fail to readdir of logical block %u of nid %llu", + i, EROFS_V(dir)->nid); + err = -EFSCORRUPTED; + break; + }

de = (struct erofs_dirent *)kmap(dentry_page);