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From:   Richard Weinberger <richard@nod.at>
To:     linux-mtd@lists.infradead.org
Cc:     linux-kernel@vger.kernel.org, Richard Weinberger <richard@nod.at>
Subject: [PATCH] ubifs: Handle LPT corruption better in ubifs_garbage_collect_leb()
Date:   Wed,  4 Jul 2018 16:02:30 +0200
Message-Id: <20180704140230.5606-1-richard@nod.at>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

If ubifs_garbage_collect_leb() notes a LPT problem, empty LEB, but
LPT has it makred as used, an ubifs_assert() is not enough.
We have to abort GC. Otherwise list_entry() returns an invalid
scan object and the kernel crashes.

c: <stable@vger.kernel.org>
Fixes: 1e51764a3c2a ("UBIFS: add new flash file system")
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 fs/ubifs/gc.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index a03a47cf880d..11c09ce3c795 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -513,7 +513,13 @@ int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp)
 	if (IS_ERR(sleb))
 		return PTR_ERR(sleb);
 
-	ubifs_assert(!list_empty(&sleb->nodes));
+	if (list_empty(&sleb->nodes)) {
+		ubifs_err(c, "Bad accouting information, LEB %i is marked as used but no nodes found!",
+			  lnum);
+		dump_stack();
+		return -EUCLEAN;
+	}
+
 	snod = list_entry(sleb->nodes.next, struct ubifs_scan_node, list);
 
 	if (snod->type == UBIFS_IDX_NODE) {
-- 
2.18.0