Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934466AbaGXJrl (ORCPT ); Thu, 24 Jul 2014 05:47:41 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:54812 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757507AbaGXJrh (ORCPT ); Thu, 24 Jul 2014 05:47:37 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Jan Kara , "Theodore Ts'o" , Luis Henriques Subject: [PATCH 3.11 050/128] ext4: Fix buffer double free in ext4_alloc_branch() Date: Thu, 24 Jul 2014 10:44:59 +0100 Message-Id: <1406195177-8656-51-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1406195177-8656-1-git-send-email-luis.henriques@canonical.com> References: <1406195177-8656-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.14 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Kara commit c5c7b8ddfbf8cb3b2291e515a34ab1b8982f5a2d upstream. Error recovery in ext4_alloc_branch() calls ext4_forget() even for buffer corresponding to indirect block it did not allocate. This leads to brelse() being called twice for that buffer (once from ext4_forget() and once from cleanup in ext4_ind_map_blocks()) leading to buffer use count misaccounting. Eventually (but often much later because there are other users of the buffer) we will see messages like: VFS: brelse: Trying to free free buffer Another manifestation of this problem is an error: JBD2 unexpected failure: jbd2_journal_revoke: !buffer_revoked(bh); inconsistent data on disk The fix is easy - don't forget buffer we did not allocate. Also add an explanatory comment because the indexing at ext4_alloc_branch() is somewhat subtle. Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Signed-off-by: Luis Henriques --- fs/ext4/indirect.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c index 87b30cd357e7..c40587735e58 100644 --- a/fs/ext4/indirect.c +++ b/fs/ext4/indirect.c @@ -390,7 +390,13 @@ static int ext4_alloc_branch(handle_t *handle, struct inode *inode, return 0; failed: for (; i >= 0; i--) { - if (i != indirect_blks && branch[i].bh) + /* + * We want to ext4_forget() only freshly allocated indirect + * blocks. Buffer for new_blocks[i-1] is at branch[i].bh and + * buffer at branch[0].bh is indirect block / inode already + * existing before ext4_alloc_branch() was called. + */ + if (i > 0 && i != indirect_blks && branch[i].bh) ext4_forget(handle, 1, inode, branch[i].bh, branch[i].bh->b_blocknr); ext4_free_blocks(handle, inode, NULL, new_blocks[i], -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/