Patch "staging: erofs: avoid endless loop of invalid lookback distance 0" has been added to the 5.3-stable tree

[gregkh at linuxfoundation.org]

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

    staging: erofs: avoid endless loop of invalid lookback distance 0

to the 5.3-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-avoid-endless-loop-of-invalid-lookback-distance-0.patch
and it can be found in the queue-5.3 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 03:24:16 PM CEST
From: Gao Xiang <gaoxiang25 at huawei.com>
Date: Wed, 9 Oct 2019 18:05:53 +0800
Subject: staging: erofs: avoid endless loop of invalid lookback distance 0
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: <20191009100554.165048-4-gaoxiang25 at huawei.com>

From: Gao Xiang <gaoxiang25 at huawei.com>

commit 598bb8913d015150b7734b55443c0e53e7189fc7 upstream.

As reported by erofs-utils fuzzer, Lookback distance should
be a positive number, so it should be actually looked back
rather than spinning.

Fixes: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter")
Cc: <stable at vger.kernel.org> # 4.19+
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Link: https://lore.kernel.org/r/20190819103426.87579-7-gaoxiang25@huawei.com
[ Gao Xiang: Since earlier kernels don't define EFSCORRUPTED,
             let's use EIO instead. ]
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/erofs/zmap.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/staging/erofs/zmap.c
+++ b/drivers/staging/erofs/zmap.c
@@ -350,6 +350,12 @@ static int vle_extent_lookback(struct z_
 
 	switch (m->type) {
 	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
+		if (!m->delta[0]) {
+			errln("invalid lookback distance 0 at nid %llu",
+			      vi->nid);
+			DBG_BUGON(1);
+			return -EIO;
+		}
 		return vle_extent_lookback(m, m->delta[0]);
 	case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
 		map->m_flags &= ~EROFS_MAP_ZIPPED;


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

queue-5.3/staging-erofs-fix-an-error-handling-in-erofs_readdir.patch
queue-5.3/staging-erofs-detect-potential-multiref-due-to-corrupted-images.patch
queue-5.3/staging-erofs-avoid-endless-loop-of-invalid-lookback-distance-0.patch
queue-5.3/staging-erofs-some-compressed-cluster-should-be-submitted-for-corrupted-images.patch
queue-5.3/staging-erofs-add-two-missing-erofs_workgroup_put-for-corrupted-images.patch