Re: FAILED: patch "[PATCH] ext4: fix leaking sysfs kobject after failed mount" failed to apply to 4.9-stable tree

[Sudip Mukherjee <sudipm.mukherjee@gmail.com>]

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Hi Greg,

On Tue, Nov 03, 2020 at 04:59:23PM +0100, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 4.9-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

Here is the backport. This will apply to both v4.9.y and v4.4.y.

--
Regards
Sudip

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From 4be70a405c3a30c8602ea7a6c58b31f905e34106 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Tue, 22 Sep 2020 09:24:56 -0700
Subject: [PATCH] ext4: fix leaking sysfs kobject after failed mount

commit cb8d53d2c97369029cc638c9274ac7be0a316c75 upstream

ext4_unregister_sysfs() only deletes the kobject.  The reference to it
needs to be put separately, like ext4_put_super() does.

This addresses the syzbot report
"memory leak in kobject_set_name_vargs (3)"
(https://syzkaller.appspot.com/bug?extid=9f864abad79fae7c17e1).

Reported-by: syzbot+9f864abad79fae7c17e1@syzkaller.appspotmail.com
Fixes: 72ba74508b28 ("ext4: release sysfs kobject when failing to enable quotas on mount")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20200922162456.93657-1-ebiggers@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
---
 fs/ext4/super.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 00391db0064b..84d28d3efc60 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4336,6 +4336,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 #ifdef CONFIG_QUOTA
 failed_mount8:
 	ext4_unregister_sysfs(sb);
+	kobject_put(&sbi->s_kobj);
 #endif
 failed_mount7:
 	ext4_unregister_li_request(sb);
-- 
2.11.0