[PATCH 05/13] xfs_repair: fix use-after-free in verify_final_dir2_path

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Way back in 2002, commit 948ce18 fixed a potential use-after-free
in verify_final_da_path, but the same fix was not applied to
verify_final_dir2_path; apply it now.

Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxxx>
---
 repair/dir2.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/repair/dir2.c b/repair/dir2.c
index 44367c6..898b27e 100644
--- a/repair/dir2.c
+++ b/repair/dir2.c
@@ -330,6 +330,7 @@ verify_final_dir2_path(xfs_mount_t	*mp,
 		const int		p_level)
 {
 	xfs_da_intnode_t	*node;
+	xfs_dahash_t		hashval;
 	int			bad = 0;
 	int			entry;
 	int			this_level = p_level + 1;
@@ -409,6 +410,12 @@ _("would correct bad hashval in non-leaf dir block\n"
 	}
 
 	/*
+	 * Note: squirrel hashval away _before_ releasing the
+	 * buffer, preventing a use-after-free problem.
+	 */
+	hashval = be32_to_cpu(btree[entry].hashval);
+
+	/*
 	 * release/write buffer
 	 */
 	ASSERT(cursor->level[this_level].dirty == 0 ||
@@ -430,7 +437,7 @@ _("would correct bad hashval in non-leaf dir block\n"
 	 * set hashvalue to correctl reflect the now-validated
 	 * last entry in this block and continue upwards validation
 	 */
-	cursor->level[this_level].hashval = be32_to_cpu(btree[entry].hashval);
+	cursor->level[this_level].hashval = hashval;
 
 	return(verify_final_dir2_path(mp, cursor, this_level));
 }
-- 
1.7.1

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