Kernel may fail to boot or devices may fail to come up when
initializing iscsi_tcp devices starting with Linux 5.8.
Marc Dionne identified the cause in RHBZ#1877345.
Commit a79af8a64d39 ("[SCSI] iscsi_tcp: use iscsi_conn_get_addr_param
libiscsi function") introduced getpeername() within the session spinlock.
Commit 1b66d253610c ("bpf: Add get{peer, sock}name attach types for
sock_addr") introduced BPF_CGROUP_RUN_SA_PROG_LOCK() within getpeername,
which acquires a mutex and when used from iscsi_tcp devices can now lead
to "BUG: scheduling while atomic:" and subsequent damage.
This commit ensures that the spinlock is released before calling
getpeername() or getsockname(). sock_hold() and sock_put() are
used to ensure that the socket reference is preserved until after
the getpeername() or getsockname() complete.
Reported-by: Marc Dionne <[email protected]>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1877345
Link: https://lkml.org/lkml/2020/7/28/1085
Link: https://lkml.org/lkml/2020/8/31/459
Fixes: a79af8a64d39 ("[SCSI] iscsi_tcp: use iscsi_conn_get_addr_param libiscsi
function")
Fixes: 1b66d253610c ("bpf: Add get{peer, sock}name attach types for sock_addr")
Signed-off-by: Mark Mielke <[email protected]>
Cc: [email protected]
---
drivers/scsi/iscsi_tcp.c | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index b5dd1caae5e9..d10efb66cf19 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -736,6 +736,7 @@ static int iscsi_sw_tcp_conn_get_param(struct
iscsi_cls_conn *cls_conn,
struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
struct sockaddr_in6 addr;
+ struct socket *sock;
int rc;
switch(param) {
@@ -747,13 +748,17 @@ static int iscsi_sw_tcp_conn_get_param(struct
iscsi_cls_conn *cls_conn,
spin_unlock_bh(&conn->session->frwd_lock);
return -ENOTCONN;
}
+ sock = tcp_sw_conn->sock;
+ sock_hold(sock->sk);
+ spin_unlock_bh(&conn->session->frwd_lock);
+
if (param == ISCSI_PARAM_LOCAL_PORT)
- rc = kernel_getsockname(tcp_sw_conn->sock,
+ rc = kernel_getsockname(sock,
(struct sockaddr *)&addr);
else
- rc = kernel_getpeername(tcp_sw_conn->sock,
+ rc = kernel_getpeername(sock,
(struct sockaddr *)&addr);
- spin_unlock_bh(&conn->session->frwd_lock);
+ sock_put(sock->sk);
if (rc < 0)
return rc;
@@ -775,6 +780,7 @@ static int iscsi_sw_tcp_host_get_param(struct Scsi_Host
*shost,
struct iscsi_tcp_conn *tcp_conn;
struct iscsi_sw_tcp_conn *tcp_sw_conn;
struct sockaddr_in6 addr;
+ struct socket *sock;
int rc;
switch (param) {
@@ -789,16 +795,18 @@ static int iscsi_sw_tcp_host_get_param(struct Scsi_Host
*shost,
return -ENOTCONN;
}
tcp_conn = conn->dd_data;
-
tcp_sw_conn = tcp_conn->dd_data;
- if (!tcp_sw_conn->sock) {
+ sock = tcp_sw_conn->sock;
+ if (!sock) {
spin_unlock_bh(&session->frwd_lock);
return -ENOTCONN;
}
+ sock_hold(sock->sk);
+ spin_unlock_bh(&session->frwd_lock);
- rc = kernel_getsockname(tcp_sw_conn->sock,
+ rc = kernel_getsockname(sock,
(struct sockaddr *)&addr);
- spin_unlock_bh(&session->frwd_lock);
+ sock_put(sock->sk);
if (rc < 0)
return rc;
--
2.28.0
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