| Message ID | 20210910010220.24073-1-dinghui@sangfor.com.cn |
|---|---|
| Headers | show |
| Series | fix several bugs about libiscsi | expand |
On 9/9/21 8:02 PM, Ding Hui wrote: > commit ec29d0ac29be ("scsi: iscsi: Fix conn use after free during > resets") move member ehwait from conn to session, but left init ehwait > in iscsi_conn_setup(). > > Due to one session can be binded by multi conns, the conn after the A session can only have 1 conn. There is some code that makes it look like we can do multiple conns or swap the single conn, but it was never fully implemented/supported upstream. However, I like the patch. The init should be done in iscsi_session_setup, so could you fix up the commit, so it's correct? > first will reinit the session->ehwait, move init ehwait to > iscsi_session_setup() to fix it. > > Fixes: ec29d0ac29be ("scsi: iscsi: Fix conn use after free during resets") > Signed-off-by: Ding Hui <dinghui@sangfor.com.cn> > --- > drivers/scsi/libiscsi.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c > index 4683c183e9d4..712a45368385 100644 > --- a/drivers/scsi/libiscsi.c > +++ b/drivers/scsi/libiscsi.c > @@ -2947,6 +2947,7 @@ iscsi_session_setup(struct iscsi_transport *iscsit, struct Scsi_Host *shost, > session->tmf_state = TMF_INITIAL; > timer_setup(&session->tmf_timer, iscsi_tmf_timedout, 0); > mutex_init(&session->eh_mutex); > + init_waitqueue_head(&session->ehwait); > > spin_lock_init(&session->frwd_lock); > spin_lock_init(&session->back_lock); > @@ -3074,8 +3075,6 @@ iscsi_conn_setup(struct iscsi_cls_session *cls_session, int dd_size, > goto login_task_data_alloc_fail; > conn->login_task->data = conn->data = data; > > - init_waitqueue_head(&session->ehwait); > - > return cls_conn; > > login_task_data_alloc_fail: >
On 9/9/21 8:02 PM, Ding Hui wrote: > like commit 5db6dd14b313 ("scsi: libiscsi: Fix NULL pointer dereference in > iscsi_eh_session_reset"), access conn->persistent_address here is not safe > too. > > The persistent_address is independent of conn refcount, so maybe > already freed by iscsi_conn_teardown(), also we put the refcount of conn > above, the conn pointer may be invalid. This shouldn't happen like you describe above, because when we wake up we will see the session->state is ISCSI_STATE_TERMINATE. We will then not reference the conn in that code below. However, it looks like we could hit an issue where if a user was resetting the persistent_address or targetname via iscsi_set_param -> iscsi_switch_str_param then we could be accessing freed memory. I think we need the frwd_lock when swapping the strings in iscsi_switch_str_param. > > Signed-off-by: Ding Hui <dinghui@sangfor.com.cn> > --- > drivers/scsi/libiscsi.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c > index 712a45368385..69b3b2148328 100644 > --- a/drivers/scsi/libiscsi.c > +++ b/drivers/scsi/libiscsi.c > @@ -2531,8 +2531,8 @@ int iscsi_eh_session_reset(struct scsi_cmnd *sc) > spin_lock_bh(&session->frwd_lock); > if (session->state == ISCSI_STATE_LOGGED_IN) { > ISCSI_DBG_EH(session, > - "session reset succeeded for %s,%s\n", > - session->targetname, conn->persistent_address); > + "session reset succeeded for %s\n", > + session->targetname); > } else > goto failed; > spin_unlock_bh(&session->frwd_lock); >
On 2021/9/11 12:25 上午, Mike Christie wrote: > On 9/9/21 8:02 PM, Ding Hui wrote: >> commit ec29d0ac29be ("scsi: iscsi: Fix conn use after free during >> resets") move member ehwait from conn to session, but left init ehwait >> in iscsi_conn_setup(). >> >> Due to one session can be binded by multi conns, the conn after the > > A session can only have 1 conn. There is some code that makes it look > like we can do multiple conns or swap the single conn, but it was never > fully implemented/supported upstream. > > However, I like the patch. The init should be done in iscsi_session_setup, > so could you fix up the commit, so it's correct? > Thanks，I'll update the commit log and send v2 1/3. >> first will reinit the session->ehwait, move init ehwait to >> iscsi_session_setup() to fix it. >> >> Fixes: ec29d0ac29be ("scsi: iscsi: Fix conn use after free during resets") >> Signed-off-by: Ding Hui <dinghui@sangfor.com.cn> >> --- >> drivers/scsi/libiscsi.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c >> index 4683c183e9d4..712a45368385 100644 >> --- a/drivers/scsi/libiscsi.c >> +++ b/drivers/scsi/libiscsi.c >> @@ -2947,6 +2947,7 @@ iscsi_session_setup(struct iscsi_transport *iscsit, struct Scsi_Host *shost, >> session->tmf_state = TMF_INITIAL; >> timer_setup(&session->tmf_timer, iscsi_tmf_timedout, 0); >> mutex_init(&session->eh_mutex); >> + init_waitqueue_head(&session->ehwait); >> >> spin_lock_init(&session->frwd_lock); >> spin_lock_init(&session->back_lock); >> @@ -3074,8 +3075,6 @@ iscsi_conn_setup(struct iscsi_cls_session *cls_session, int dd_size, >> goto login_task_data_alloc_fail; >> conn->login_task->data = conn->data = data; >> >> - init_waitqueue_head(&session->ehwait); >> - >> return cls_conn; >> >> login_task_data_alloc_fail: >> > -- Thanks, -dinghui
On 2021/9/11 12:38 上午, Mike Christie wrote: > On 9/9/21 8:02 PM, Ding Hui wrote: >> like commit 5db6dd14b313 ("scsi: libiscsi: Fix NULL pointer dereference in >> iscsi_eh_session_reset"), access conn->persistent_address here is not safe >> too. >> >> The persistent_address is independent of conn refcount, so maybe >> already freed by iscsi_conn_teardown(), also we put the refcount of conn >> above, the conn pointer may be invalid. > > This shouldn't happen like you describe above, because when we wake up > we will see the session->state is ISCSI_STATE_TERMINATE. We will then > not reference the conn in that code below. > > However, it looks like we could hit an issue where if a user was resetting > the persistent_address or targetname via iscsi_set_param -> iscsi_switch_str_param > then we could be accessing freed memory. I think we need the frwd_lock when swapping > the strings in iscsi_switch_str_param. > Thanks for your detailed explanation, I'll drop 2/3 and 3/3 in v2 patch. I expect that the persistent_address issue be fixed in your future patchset. Sorry for my ignorance. > >> >> Signed-off-by: Ding Hui <dinghui@sangfor.com.cn> >> --- >> drivers/scsi/libiscsi.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c >> index 712a45368385..69b3b2148328 100644 >> --- a/drivers/scsi/libiscsi.c >> +++ b/drivers/scsi/libiscsi.c >> @@ -2531,8 +2531,8 @@ int iscsi_eh_session_reset(struct scsi_cmnd *sc) >> spin_lock_bh(&session->frwd_lock); >> if (session->state == ISCSI_STATE_LOGGED_IN) { >> ISCSI_DBG_EH(session, >> - "session reset succeeded for %s,%s\n", >> - session->targetname, conn->persistent_address); >> + "session reset succeeded for %s\n", >> + session->targetname); >> } else >> goto failed; >> spin_unlock_bh(&session->frwd_lock); >> > -- Thanks, -dinghui
Ding Hui (3): scsi: libiscsi: move init ehwait to iscsi_session_setup() scsi: libiscsi: fix invalid pointer dereference in iscsi_eh_session_reset scsi: libiscsi: get ref to conn in iscsi_eh_device/target_reset() drivers/scsi/libiscsi.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)