From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: [PATCH 1/2] ext4: Avoid crashing on NULL ptr dereference on a filesystem error Date: Tue, 25 May 2010 00:18:36 -0400 Message-ID: <1274761117-26560-1-git-send-email-tytso@mit.edu> References: <20100525041737.GB5556@thunk.org> Cc: Theodore Ts'o To: Ext4 Developers List Return-path: Received: from thunk.org ([69.25.196.29]:49557 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750815Ab0EYESj (ORCPT ); Tue, 25 May 2010 00:18:39 -0400 In-Reply-To: <20100525041737.GB5556@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: If the EOFBLOCK_FL flag is set when it should not be and the inode is zero length, then eh_entries is zero, and ex is NULL, so dereferencing ex to print ex->ee_block causes a kernel OOPS in ext4_ext_map_blocks(). On top of that, the error message which is printed isn't very helpful. So we fix this by printing something more explanatory which doesn't involve trying to print ex->ee_block. Addresses-Google-Bug: #2655740 Signed-off-by: "Theodore Ts'o" --- fs/ext4/extents.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 595ab6d..aeec5c7 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3370,8 +3370,9 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, */ if (unlikely(path[depth].p_ext == NULL && depth != 0)) { EXT4_ERROR_INODE(inode, "bad extent address " - "iblock: %d, depth: %d pblock %lld", - map->m_lblk, depth, path[depth].p_block); + "lblock: %lu, depth: %d pblock %lld", + (unsigned long) map->m_lblk, depth, + path[depth].p_block); err = -EIO; goto out2; } @@ -3501,8 +3502,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, if (unlikely(ext4_test_inode_flag(inode, EXT4_INODE_EOFBLOCKS))) { if (unlikely(!eh->eh_entries)) { EXT4_ERROR_INODE(inode, - "eh->eh_entries == 0 ee_block %d", - ex->ee_block); + "eh->eh_entries == 0 and " + "EOFBLOCKS_FL set"); err = -EIO; goto out2; } -- 1.6.6.1.1.g974db.dirty