releases/5.15.112/ksmbd-fix-kernel-oops-from-idr_remove.patch

From e422c48bc373790c7a99f05459d85a5335552b26 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Fri, 22 Jul 2022 10:17:06 +0900
Subject: ksmbd: fix kernel oops from idr_remove()

From: Namjae Jeon <linkinjeon@kernel.org>

[ Upstream commit 17ea92a9f6d0b9a97aaec5ab748e4591d70a562c ]

There is a report that kernel oops happen from idr_remove().

kernel: BUG: kernel NULL pointer dereference, address: 0000000000000010
kernel: RIP: 0010:idr_remove+0x1/0x20
kernel:  __ksmbd_close_fd+0xb2/0x2d0 [ksmbd]
kernel:  ksmbd_vfs_read+0x91/0x190 [ksmbd]
kernel:  ksmbd_fd_put+0x29/0x40 [ksmbd]
kernel:  smb2_read+0x210/0x390 [ksmbd]
kernel:  __process_request+0xa4/0x180 [ksmbd]
kernel:  __handle_ksmbd_work+0xf0/0x290 [ksmbd]
kernel:  handle_ksmbd_work+0x2d/0x50 [ksmbd]
kernel:  process_one_work+0x21d/0x3f0
kernel:  worker_thread+0x50/0x3d0
kernel:  rescuer_thread+0x390/0x390
kernel:  kthread+0xee/0x120
kthread_complete_and_exit+0x20/0x20
kernel:  ret_from_fork+0x22/0x30

While accessing files, If connection is disconnected, windows send
session setup request included previous session destroy. But while still
processing requests on previous session, this request destroy file
table, which mean file table idr will be freed and set to NULL.
So kernel oops happen from ft->idr in __ksmbd_close_fd().
This patch don't directly destroy session in destroy_previous_session().
It just set to KSMBD_SESS_EXITING so that connection will be
terminated after finishing the rest of requests.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Stable-dep-of: 7b4323373d84 ("ksmbd: fix deadlock in ksmbd_find_crypto_ctx()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ksmbd/mgmt/user_session.c | 2 ++
 fs/ksmbd/smb2pdu.c           | 8 ++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/ksmbd/mgmt/user_session.c b/fs/ksmbd/mgmt/user_session.c
index 0c7b5335c12af..9c4a9c8c02795 100644
--- a/fs/ksmbd/mgmt/user_session.c
+++ b/fs/ksmbd/mgmt/user_session.c
@@ -241,6 +241,8 @@ struct ksmbd_session *ksmbd_session_lookup_all(struct ksmbd_conn *conn,
 	sess = ksmbd_session_lookup(conn, id);
 	if (!sess && conn->binding)
 		sess = ksmbd_session_lookup_slowpath(id);
+	if (sess && sess->state != SMB2_SESSION_VALID)
+		sess = NULL;
 	return sess;
 }
 
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index e17f7a5dd9974..8bfe2a6c05f92 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -600,6 +600,7 @@ static void destroy_previous_session(struct ksmbd_conn *conn,
 {
 	struct ksmbd_session *prev_sess = ksmbd_session_lookup_slowpath(id);
 	struct ksmbd_user *prev_user;
+	struct channel *chann;
 
 	if (!prev_sess)
 		return;
@@ -615,8 +616,11 @@ static void destroy_previous_session(struct ksmbd_conn *conn,
 	}
 
 	put_session(prev_sess);
-	xa_erase(&conn->sessions, prev_sess->id);
-	ksmbd_session_destroy(prev_sess);
+	prev_sess->state = SMB2_SESSION_EXPIRED;
+	write_lock(&prev_sess->chann_lock);
+	list_for_each_entry(chann, &prev_sess->ksmbd_chann_list, chann_list)
+		chann->conn->status = KSMBD_SESS_EXITING;
+	write_unlock(&prev_sess->chann_lock);
 }
 
 /**
-- 
2.39.2