linux-ext4 - [PATCH] e2fsck: Fix access after free for dx

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Message-Id: <20171030133214.24279-1-artem.blagodarenko@gmail.com>
Date:   Mon, 30 Oct 2017 16:32:14 +0300
From:   Artem Blagodarenko <artem.blagodarenko@...il.com>
To:     linux-ext4@...r.kernel.org
Cc:     adilger.kernel@...ger.ca
Subject: [PATCH] e2fsck: Fix access after free for dx_db structure

dx_db structure is freed after fixing of PR_2_HTREE_BAD_ROOT
problem. Next code block use this structure to unerstand if leaf
is beeng processed.

If dx_db is freed, then root block is being processed and if_leaf
need to be set to 0.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@...il.com>
---
 e2fsck/pass2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
index 09c16179..7bda37a7 100644
--- a/e2fsck/pass2.c
+++ b/e2fsck/pass2.c
@@ -1109,7 +1109,7 @@ inline_read_fail:
 			    ((fs->blocksize - (8 + dx_csum_size)) /
 			     sizeof(struct ext2_dx_entry))))
 			dx_db->type = DX_DIRBLOCK_NODE;
-		is_leaf = (dx_db->type == DX_DIRBLOCK_LEAF);
+		is_leaf = dx_db ? (dx_db->type == DX_DIRBLOCK_LEAF) : 0;
 	}
 out_htree:
 
-- 
2.13.5 (Apple Git-94)