From: Theodore Ts'o <tytso@mit.edu>
Date: Fri, 5 May 2023 22:20:29 -0400
Subject: [PATCH] ext4: improve error recovery code paths in __ext4_remount()
References: bsc#1012628
Patch-mainline: 6.3.3
Git-commit: 4c0b4818b1f636bc96359f7817a2d8bab6370162

commit 4c0b4818b1f636bc96359f7817a2d8bab6370162 upstream.

If there are failures while changing the mount options in
__ext4_remount(), we need to restore the old mount options.

This commit fixes two problem.  The first is there is a chance that we
will free the old quota file names before a potential failure leading
to a use-after-free.  The second problem addressed in this commit is
if there is a failed read/write to read-only transition, if the quota
has already been suspended, we need to renable quota handling.

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230506142419.984260-2-tytso@mit.edu
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 fs/ext4/super.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 88240a16..d6ac61f4 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6579,9 +6579,6 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
 	}
 
 #ifdef CONFIG_QUOTA
-	/* Release old quota file names */
-	for (i = 0; i < EXT4_MAXQUOTAS; i++)
-		kfree(old_opts.s_qf_names[i]);
 	if (enable_quota) {
 		if (sb_any_quota_suspended(sb))
 			dquot_resume(sb, -1);
@@ -6591,6 +6588,9 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
 				goto restore_opts;
 		}
 	}
+	/* Release old quota file names */
+	for (i = 0; i < EXT4_MAXQUOTAS; i++)
+		kfree(old_opts.s_qf_names[i]);
 #endif
 	if (!test_opt(sb, BLOCK_VALIDITY) && sbi->s_system_blks)
 		ext4_release_system_zone(sb);
@@ -6601,6 +6601,13 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
 	return 0;
 
 restore_opts:
+	/*
+	 * If there was a failing r/w to ro transition, we may need to
+	 * re-enable quota
+	 */
+	if ((sb->s_flags & SB_RDONLY) && !(old_sb_flags & SB_RDONLY) &&
+	    sb_any_quota_suspended(sb))
+		dquot_resume(sb, -1);
 	sb->s_flags = old_sb_flags;
 	sbi->s_mount_opt = old_opts.s_mount_opt;
 	sbi->s_mount_opt2 = old_opts.s_mount_opt2;
-- 
2.35.3