linux-kernel - [PATCH 4.9 18/35] ext4: fix superblock checksum failure when setting password salt

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Message-Id: <20210122135733.057654705@linuxfoundation.org>
Date:   Fri, 22 Jan 2021 15:10:20 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Michael Halcrow <mhalcrow@...gle.com>,
        Andreas Dilger <adilger@...ger.ca>, Jan Kara <jack@...e.cz>,
        Theodore Tso <tytso@....edu>
Subject: [PATCH 4.9 18/35] ext4: fix superblock checksum failure when setting password salt

From: Jan Kara <jack@...e.cz>

commit dfd56c2c0c0dbb11be939b804ddc8d5395ab3432 upstream.

When setting password salt in the superblock, we forget to recompute the
superblock checksum so it will not match until the next superblock
modification which recomputes the checksum. Fix it.

CC: Michael Halcrow <mhalcrow@...gle.com>
Reported-by: Andreas Dilger <adilger@...ger.ca>
Fixes: 9bd8212f981e ("ext4 crypto: add encryption policy and password salt support")
Signed-off-by: Jan Kara <jack@...e.cz>
Link: https://lore.kernel.org/r/20201216101844.22917-8-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/ext4/ioctl.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -799,7 +799,10 @@ resizefs_out:
 			err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 			if (err)
 				goto pwsalt_err_journal;
+			lock_buffer(sbi->s_sbh);
 			generate_random_uuid(sbi->s_es->s_encrypt_pw_salt);
+			ext4_superblock_csum_set(sb);
+			unlock_buffer(sbi->s_sbh);
 			err = ext4_handle_dirty_metadata(handle, NULL,
 							 sbi->s_sbh);
 		pwsalt_err_journal: