linux-ext4 - [PATCH 4/5] ext4: fix block validity checks for journal inodes using indirect blocks

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Date:   Thu, 30 Apr 2020 00:51:38 +0530
From:   ashwin-h <ashwinh@...are.com>
To:     <tytso@....edu>, <adilger.kernel@...ger.ca>
CC:     <linux-ext4@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <stable@...nel.org>, <srivatsab@...are.com>,
        <srivatsa@...il.mit.edu>, <rostedt@...dmis.org>,
        <srostedt@...are.com>, <gregkh@...uxfoundation.org>,
        <ashwin.hiranniah@...il.com>, Ashwin H <ashwinh@...are.com>
Subject: [PATCH 4/5] ext4: fix block validity checks for journal inodes using indirect blocks

From: Theodore Ts'o <tytso@....edu>

commit 170417c8c7bb2cbbdd949bf5c443c0c8f24a203b upstream.

Commit 345c0dbf3a30 ("ext4: protect journal inode's blocks using
block_validity") failed to add an exception for the journal inode in
ext4_check_blockref(), which is the function used by ext4_get_branch()
for indirect blocks.  This caused attempts to read from the ext3-style
journals to fail with:

[  848.968550] EXT4-fs error (device sdb7): ext4_get_branch:171: inode #8: block 30343695: comm jbd2/sdb7-8: invalid block

Fix this by adding the missing exception check.

Fixes: 345c0dbf3a30 ("ext4: protect journal inode's blocks using block_validity")
Reported-by: Arthur Marsh <arthur.marsh@...ernode.on.net>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Ashwin H <ashwinh@...are.com>
---
 fs/ext4/block_validity.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index bdc8e48..9c9c639 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -274,6 +274,11 @@ int ext4_check_blockref(const char *function, unsigned int line,
 	__le32 *bref = p;
 	unsigned int blk;
 
+	if (ext4_has_feature_journal(inode->i_sb) &&
+	    (inode->i_ino ==
+	     le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
+		return 0;
+
 	while (bref < p+max) {
 		blk = le32_to_cpu(*bref++);
 		if (blk &&
-- 
2.7.4