From: Theodore Ts'o Subject: [PATCH 2.6.33.y 35/40] ext4: Avoid crashing on NULL ptr dereference on a filesystem error Date: Tue, 1 Jun 2010 08:03:22 -0400 Message-ID: <1275393807-14369-35-git-send-email-tytso@mit.edu> References: <1275393807-14369-1-git-send-email-tytso@mit.edu> Cc: Ext4 Developers List , Theodore Ts'o To: stable@vger.kernel.org Return-path: Received: from THUNK.ORG ([69.25.196.29]:47285 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756076Ab0FAMDd (ORCPT ); Tue, 1 Jun 2010 08:03:33 -0400 In-Reply-To: <1275393807-14369-1-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: commit f70f362b4a6fe47c239dbfb3efc0cc2c10e4f09c upstream (as of v2.6.34-git13) 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 | 11 +++++++---- 1 files changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 5b1c104..e2d9bfb 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3275,8 +3275,8 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, */ if (path[depth].p_ext == NULL && depth != 0) { ext4_error(inode->i_sb, __func__, "bad extent address " - "inode: %lu, iblock: %d, depth: %d", - inode->i_ino, iblock, depth); + "inode: %lu, iblock: %lu, depth: %d", + inode->i_ino, (unsigned long) iblock, depth); err = -EIO; goto out2; } @@ -3412,8 +3412,11 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, } else { WARN_ON(eh->eh_entries == 0); ext4_error(inode->i_sb, __func__, - "inode#%lu, eh->eh_entries = 0!", inode->i_ino); - } + "inode#%lu, eh->eh_entries = 0 and " + "EOFBLOCKS_FL set", inode->i_ino); + err = -EIO; + goto out2; + } } err = ext4_ext_insert_extent(handle, inode, path, &newex, flags); if (err) { -- 1.6.6.1.1.g974db.dirty