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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+187510916eb6a14598f7@syzkaller.appspotmail.com,
        Eric Biggers <ebiggers@google.com>, Jan Kara <jack@suse.cz>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 096/112] reiserfs: only call unlock_new_inode() if I_NEW
Date:   Tue, 27 Oct 2020 14:50:06 +0100
Message-Id: <20201027134905.081151837@linuxfoundation.org>
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From: Eric Biggers <ebiggers@google.com>

[ Upstream commit 8859bf2b1278d064a139e3031451524a49a56bd0 ]

unlock_new_inode() is only meant to be called after a new inode has
already been inserted into the hash table.  But reiserfs_new_inode() can
call it even before it has inserted the inode, triggering the WARNING in
unlock_new_inode().  Fix this by only calling unlock_new_inode() if the
inode has the I_NEW flag set, indicating that it's in the table.

This addresses the syzbot report "WARNING in unlock_new_inode"
(https://syzkaller.appspot.com/bug?extid=187510916eb6a14598f7).

Link: https://lore.kernel.org/r/20200628070057.820213-1-ebiggers@kernel.org
Reported-by: syzbot+187510916eb6a14598f7@syzkaller.appspotmail.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/reiserfs/inode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index cfb4691d92741..ccbb15ab029f4 100644
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -2157,7 +2157,8 @@ int reiserfs_new_inode(struct reiserfs_transaction_handle *th,
 out_inserted_sd:
 	clear_nlink(inode);
 	th->t_trans_id = 0;	/* so the caller can't use this handle later */
-	unlock_new_inode(inode); /* OK to do even if we hadn't locked it */
+	if (inode->i_state & I_NEW)
+		unlock_new_inode(inode);
 	iput(inode);
 	return err;
 }
-- 
2.25.1