Commit 12486ef7 authored by Dennis Lam's avatar Dennis Lam Committed by Xiangwei Li
Browse files

ocfs2: fix slab-use-after-free due to dangling pointer dqi_priv 

mainline inclusion
from mainline-v6.13-rc6
commit 5f3fd772d152229d94602bca243fbb658068a597
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBID30
CVE: CVE-2024-57892

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5f3fd772d152229d94602bca243fbb658068a597

-------------------------------------

When mounting ocfs2 and then remounting it as read-only, a
slab-use-after-free occurs after the user uses a syscall to
quota_getnextquota.  Specifically, sb_dqinfo(sb, type)->dqi_priv is the
dangling pointer.

During the remounting process, the pointer dqi_priv is freed but is never
set as null leaving it to be accessed.  Additionally, the read-only option
for remounting sets the DQUOT_SUSPENDED flag instead of setting the
DQUOT_USAGE_ENABLED flags.  Moreover, later in the process of getting the
next quota, the function ocfs2_get_next_id is called and only checks the
quota usage flags and not the quota suspended flags.

To fix this, I set dqi_priv to null when it is freed after remounting with
read-only and put a check for DQUOT_SUSPENDED in ocfs2_get_next_id.

[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20241218023924.22821-2-dennis.lamerice@gmail.com


Fixes: 8f9e8f5f ("ocfs2: Fix Q_GETNEXTQUOTA for filesystem without quotas")
Signed-off-by: default avatarDennis Lam <dennis.lamerice@gmail.com>
Reported-by: default avatar <syzbot+d173bf8a5a7faeede34c@syzkaller.appspotmail.com>
Tested-by: default avatar <syzbot+d173bf8a5a7faeede34c@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/all/6731d26f.050a0220.1fb99c.014b.GAE@google.com/T/


Reviewed-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarXiangwei Li <liwei728@huawei.com>
parent bb363f13

fs/ocfs2/quota_global.c

+1 −1
Original line number Diff line number Diff line
@@ -881,7 +881,7 @@ static int ocfs2_get_next_id(struct super_block *sb, struct kqid *qid) 
	int status = 0;



	trace_ocfs2_get_next_id(from_kqid(&init_user_ns, *qid), type);

	if (!sb_has_quota_loaded(sb, type)) {

	if (!sb_has_quota_active(sb, type)) {

		status = -ESRCH;

		goto out;

	}

fs/ocfs2/quota_local.c

+1 −0
Original line number Diff line number Diff line
@@ -860,6 +860,7 @@ static int ocfs2_local_free_info(struct super_block *sb, int type) 
	brelse(oinfo->dqi_libh);

	brelse(oinfo->dqi_lqi_bh);

	kfree(oinfo);

	info->dqi_priv = NULL;

	return status;

}