From: Namjae Jeon <linkinjeon@xxxxxxxxxx>
commit 83dcedd5540d4ac61376ddff5362f7d9f866a6ec upstream.
If kernel_recvmsg() return -EAGAIN in ksmbd_tcp_readv() and go round
again, It will cause infinite loop issue. And all threads from next
connections would be doing that. This patch add max retry count(2) to
avoid it. kernel_recvmsg() will wait during 7sec timeout and try to
retry two time if -EAGAIN is returned. And add flags of kvmalloc to
__GFP_NOWARN and __GFP_NORETRY to disconnect immediately without
retrying on memory alloation failure.
Fixes: 0626e6641f6b ("cifsd: add server handler for central processing and tranport layers")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: zdi-disclosures@xxxxxxxxxxxxxx # ZDI-CAN-18259
Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ksmbd/connection.c | 7 +++++--
fs/ksmbd/transport_tcp.c | 5 ++++-
2 files changed, 9 insertions(+), 3 deletions(-)
--- a/fs/ksmbd/connection.c
+++ b/fs/ksmbd/connection.c
@@ -310,9 +310,12 @@ int ksmbd_conn_handler_loop(void *p)
/* 4 for rfc1002 length field */
size = pdu_size + 4;
- conn->request_buf = kvmalloc(size, GFP_KERNEL);
+ conn->request_buf = kvmalloc(size,
+ GFP_KERNEL |
+ __GFP_NOWARN |
+ __GFP_NORETRY);
if (!conn->request_buf)
- continue;
+ break;
memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf));
if (!ksmbd_smb_request(conn))
--- a/fs/ksmbd/transport_tcp.c
+++ b/fs/ksmbd/transport_tcp.c
@@ -295,6 +295,7 @@ static int ksmbd_tcp_readv(struct tcp_tr
struct msghdr ksmbd_msg;
struct kvec *iov;
struct ksmbd_conn *conn = KSMBD_TRANS(t)->conn;
+ int max_retry = 2;
iov = get_conn_iovec(t, nr_segs);
if (!iov)
@@ -321,9 +322,11 @@ static int ksmbd_tcp_readv(struct tcp_tr
} else if (conn->status == KSMBD_SESS_NEED_RECONNECT) {
total_read = -EAGAIN;
break;
- } else if (length == -ERESTARTSYS || length == -EAGAIN) {
+ } else if ((length == -ERESTARTSYS || length == -EAGAIN) &&
+ max_retry) {
usleep_range(1000, 2000);
length = 0;
+ max_retry--;
continue;
} else if (length <= 0) {
total_read = -EAGAIN;
