From 2803cf4379ed252894f046cb8812a48db35294e3 Mon Sep 17 00:00:00 2001
From: Gertjan Halkes <gertjan@google.com>
Date: Wed, 5 Sep 2018 15:41:29 +0900
Subject: 9p: do not trust pdu content for stat item size

v9fs_dir_readdir() could deadloop if a struct was sent with a size set
to -2

Link: http://lkml.kernel.org/r/1536134432-11997-1-git-send-email-asmadeus@codewreck.org
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88021
Signed-off-by: Gertjan Halkes <gertjan@google.com>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
---
 net/9p/protocol.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'net/9p')

diff --git a/net/9p/protocol.c b/net/9p/protocol.c
index ee32bbf12675..b4d80c533f89 100644
--- a/net/9p/protocol.c
+++ b/net/9p/protocol.c
@@ -571,9 +571,10 @@ int p9stat_read(struct p9_client *clnt, char *buf, int len, struct p9_wstat *st)
 	if (ret) {
 		p9_debug(P9_DEBUG_9P, "<<< p9stat_read failed: %d\n", ret);
 		trace_9p_protocol_dump(clnt, &fake_pdu);
+		return ret;
 	}
 
-	return ret;
+	return fake_pdu.offset;
 }
 EXPORT_SYMBOL(p9stat_read);
 
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