From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794590402; b=BhAhbWOArpsC2F0C3Xf9+WTFgzNWQJ7HK+9BD38D4jwLCAFiGau4BxpW9ijyVVaDxfCf XKYOXnydJ75pCi8vEx4TFNH9hhU3IDXnPyxEuiHfFHlMyXgUPyf9cqMAjaOXGwaMD1L/q zB74SzNPtY5uCFv8mNQ5Hy/0r9MoAUbqnBnzX5qjpwLcMupulTsg8CmEBpr8bSJUNNfId HdumGMWXTUT+KiYRgtFNe7c8zjqInW8urK3h9F2PvWPND37eAJSHYZH4ensiOPVz56Eme yfyqZjovJ5vghV+c7qTyGtoBlpC9vhu0eYguHQzkXdiWMO2fkLtDRCz32u02X5NN9wA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794590402; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=hz3kfPvtlJqYHEl7tCiEGvLIuL7vTctBeHWAkvxSbJ0=; b=OXp8I+5E0ejaafBmGSpEofqCNtiHNai7ZhtX/z4/mbRE41QGbdFrAfE0SillgGU5NvEH 0j0IByf74ZfgQ6XC/SNHNNZ6v5QBotX6+nUOyjZYrr9lLibO2e2KTcAxqPK/fVSlqp5+Q jyFwHgJ1G5sxEfBXPsR/MwmDX0w4fPZM/o4MWeWvti19wrlrpIDftkByawm89w6GfnZBk ptDWxjwLKBW1lXiV9GgtN3eSiVbijPHy8hjFbcOLWBVVsabxM6ZloRt0JWp+kq9clzx2C MpOvta9wfWT3vmuBXqp7BZcz6jZOnkMKPn143xIVGYnLFoUrPQClRufe0ZSLf9hskdw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=GdubCcSe; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 44817606B451; Fri, 13 Nov 2026 17:20:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=GdubCcSe Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5BAE1F000C4; Fri, 13 Nov 2026 17:20:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794590402; bh=hz3kfPvtlJqYHEl7tCiEGvLIuL7vTctBeHWAkvxSbJ0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GdubCcSeWmiGzIyY/77GNFV7QMkBFZucwyozfSsaQV5Us8DQa6x6+VhJG+BVeFge4 rgV3c3Aet2+3lLk8STeCmHlhRpso+xnywGewJNTs3jwNBQvWQDUO8shu3UWlg25IRh 7G0zRPBlF5qxnqORYGVKWNhTZPcK/msXKrGW2fxA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Joseph Qi , Andrew Morton , Heming Zhao , Mark Fasheh , Joel Becker , Sasha Levin Subject: [PATCH 6.18 327/686] ocfs2: do not index before the entry array when dividing an empty bucket Date: Fri, 13 Nov 2026 10:47:40 -0500 Message-ID: <20261113153832.007466157@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153820.902362109@linuxfoundation.org> References: <20261113153820.902362109@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Joseph Qi [ Upstream commit 7133a0d0954c109f1764ebf8ab32d7e757a6c587 ] ocfs2_divide_xattr_bucket() appends an empty bucket carrying a sentinel hash when the source bucket has no divide position, taking that hash from xh_entries[start - 1]. ocfs2_xattr_find_divide_pos() returns count when every entry shares one hash, and its loop does not run at all for count < 2, so an empty bucket comes back with start == count == 0 and the read is xh_entries[-1]. That is outside the __counted_by_le(xh_count) bounds of xh_entries[] and lands on the header, so the value picked up is xh_count | xh_free_start << 16. One above it is written into the new bucket's xh_entries[0] and committed, which leaves a bucket whose first hash does not follow the bucket before it. ocfs2_xattr_bucket_find() binary searches on xh_entries[0], so the broken key hides the range the sentinel was meant to cover: getxattr() answers -ENODATA for an attribute that is stored, and an insert can go to the wrong bucket and leave two copies of a name. The cross cluster divide hands the same value back as a tree record's e_cpos, which then claims a hash range it does not cover. Read xh_entries[0] instead. The branch is only reached when every entry shares one hash, so for a non-empty bucket it holds the same value, and for an empty one it is the slot that carries the bucket key. An empty bucket reaches the divide from ocfs2_check_xattr_bucket_collision(), which reports no collision for one, through ocfs2_add_new_xattr_bucket() and ocfs2_extend_xattr_bucket(). It does not take a failed set to get there: a divide that finds no position is itself what leaves an empty sentinel bucket behind, and a later extend can pick it as the target. Link: https://lore.kernel.org/20261024151012.1059683-6-joseph.qi@linux.alibaba.com Fixes: 80bcaf3469b8 ("ocfs2/xattr: Proper hash collision handle in bucket division") Signed-off-by: Joseph Qi Signed-off-by: Andrew Morton Cc: Heming Zhao Cc: Mark Fasheh Cc: Joel Becker Cc: Signed-off-by: Sasha Levin --- fs/ocfs2/xattr.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c index a82fb4a5084c3..5f263d24bbc3b 100644 --- a/fs/ocfs2/xattr.c +++ b/fs/ocfs2/xattr.c @@ -4814,7 +4814,15 @@ static int ocfs2_divide_xattr_bucket(struct inode *inode, start = ocfs2_xattr_find_divide_pos(xh); if (start == count) { - xe = &xh->xh_entries[start-1]; + /* + * start == count means every entry shares one hash, so the + * first of them carries it too. An empty bucket has no + * entries[start - 1], but its entries[0] still carries the + * bucket key: either the hash ocfs2_xa_remove_entry() + * deliberately leaves behind, or the sentinel a previous + * divide wrote. + */ + xe = &xh->xh_entries[0]; /* * initialized a new empty bucket here. -- 2.53.0