From e735dbd489e3ea02be78dba991056fe1138be51e Mon Sep 17 00:00:00 2001 From: Gil Portnoy Date: Thu, 28 May 2026 00:00:00 +0000 Subject: [PATCH] ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers [ Upstream commit b003086d76968298f22e7cf62239833b5a3a06b1 ] smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn into a local with neither READ_ONCE() nor a NULL check. Both run from oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then writes through NULL at offset 0xc4 -- a remotely triggerable oops. Guard both reads the way compare_guid_key() already does: read opinfo->conn with READ_ONCE() and return early if it is NULL, before allocating the work struct so nothing leaks. A NULL conn means the client is gone and the break is moot, so return 0; oplock_break() treats that as success and runs the normal teardown. Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Assisted-by: Henry (Claude):claude-opus-4 Signed-off-by: Gil Portnoy Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/smb/server/oplock.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/fs/smb/server/oplock.c b/fs/smb/server/oplock.c index a84c01bceb8b..6454c7a4baa4 100644 --- a/fs/smb/server/oplock.c +++ b/fs/smb/server/oplock.c @@ -714,11 +714,16 @@ out: */ static int smb2_oplock_break_noti(struct oplock_info *opinfo) { - struct ksmbd_conn *conn = opinfo->conn; + struct ksmbd_conn *conn; struct oplock_break_info *br_info; int ret = 0; - struct ksmbd_work *work = ksmbd_alloc_work_struct(); + struct ksmbd_work *work; + conn = READ_ONCE(opinfo->conn); + if (!conn) + return 0; + + work = ksmbd_alloc_work_struct(); if (!work) return -ENOMEM; @@ -818,11 +823,15 @@ out: */ static int smb2_lease_break_noti(struct oplock_info *opinfo) { - struct ksmbd_conn *conn = opinfo->conn; + struct ksmbd_conn *conn; struct ksmbd_work *work; struct lease_break_info *br_info; struct lease *lease = opinfo->o_lease; + conn = READ_ONCE(opinfo->conn); + if (!conn) + return 0; + work = ksmbd_alloc_work_struct(); if (!work) return -ENOMEM;