Patch "staging: erofs: fix an error handling in erofs_readdir()" has been added to the 4.19-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    staging: erofs: fix an error handling in erofs_readdir()

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     staging-erofs-fix-an-error-handling-in-erofs_readdir.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Wed 09 Oct 2019 03:26:06 PM CEST
From: Gao Xiang <gaoxiang25 at huawei.com>
Date: Wed, 9 Oct 2019 18:12:36 +0800
Subject: staging: erofs: fix an error handling in erofs_readdir()
To: Greg Kroah-Hartman <gregkh at linuxfoundation.org>, <stable at vger.kernel.org>, Chao Yu <yuchao0 at huawei.com>
Cc: <linux-erofs at lists.ozlabs.org>, Miao Xie <miaoxie at huawei.com>, Gao Xiang <gaoxiang25 at huawei.com>
Message-ID: <20191009101239.195587-1-gaoxiang25 at huawei.com>

From: Gao Xiang <gaoxiang25 at huawei.com>

commit acb383f1dcb4f1e79b66d4be3a0b6f519a957b0d upstream.

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.at/

Reported-by: Richard Weinberger <richard at nod.at>
Fixes: 3aa8ec716e52 ("staging: erofs: add directory operations")
Cc: <stable at vger.kernel.org> # 4.19+
Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
Link: https://lore.kernel.org/r/20190818125457.25906-1-hsiangkao@aol.com
[ Gao Xiang: Since earlier kernels don't define EFSCORRUPTED,
             let's use original error code instead. ]
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/erofs/dir.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/staging/erofs/dir.c
+++ b/drivers/staging/erofs/dir.c
@@ -100,8 +100,15 @@ static int erofs_readdir(struct file *f,
 		unsigned 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 = PTR_ERR(dentry_page);
+			break;
+		}
 
 		lock_page(dentry_page);
 		de = (struct erofs_dirent *)kmap(dentry_page);


Patches currently in stable-queue which might be from gaoxiang25 at huawei.com are

queue-4.19/staging-erofs-fix-an-error-handling-in-erofs_readdir.patch
queue-4.19/staging-erofs-detect-potential-multiref-due-to-corrupted-images.patch
queue-4.19/staging-erofs-some-compressed-cluster-should-be-submitted-for-corrupted-images.patch
queue-4.19/staging-erofs-add-two-missing-erofs_workgroup_put-for-corrupted-images.patch