Commit d962f01a authored by Namjae Jeon's avatar Namjae Jeon Committed by ZhaoLong Wang
Browse files

ksmbd: fix infinite loop in ksmbd_conn_handler_loop() 

mainline inclusion
from mainline-v6.2-rc4
commit 83dcedd5
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I74FNG
CVE: CVE-2023-2593

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=83dcedd5540d4ac61376ddff5362f7d9f866a6ec



--------------------------------

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: 0626e664 ("cifsd: add server handler for central processing and tranport layers")
Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-18259
Reviewed-by: default avatarSergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
Signed-off-by: default avatarZhaoLong Wang <wangzhaolong1@huawei.com>

Conflicts:
  fs/ksmbd/connection.c
  fs/ksmbd/transport_tcp.c
parent ed1f75af

fs/ksmbd/connection.c

+5 −2
Original line number Original line Diff line number Diff line
@@ -352,9 +352,12 @@ int ksmbd_conn_handler_loop(void *p) 
		/* 4 for rfc1002 length field */

		/* 4 for rfc1002 length field */

		/* 1 for implied bcc[0] */

		/* 1 for implied bcc[0] */

		size = pdu_size + 4 + 1;

		size = pdu_size + 4 + 1;

		conn->request_buf = kvmalloc(size, GFP_KERNEL);

		conn->request_buf = kvmalloc(size,

					     GFP_KERNEL |

					     __GFP_NOWARN |

					     __GFP_NORETRY);

		if (!conn->request_buf)

		if (!conn->request_buf)

			continue;

			break;





		memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf));

		memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf));

fs/ksmbd/transport_tcp.c

+4 −1
Original line number Original line Diff line number Diff line
@@ -295,6 +295,7 @@ static int ksmbd_tcp_readv(struct tcp_transport *t, struct kvec *iov_orig, 
	struct msghdr ksmbd_msg;

	struct msghdr ksmbd_msg;

	struct kvec *iov;

	struct kvec *iov;

	struct ksmbd_conn *conn = KSMBD_TRANS(t)->conn;

	struct ksmbd_conn *conn = KSMBD_TRANS(t)->conn;

	int max_retry = 2;





	iov = get_conn_iovec(t, nr_segs);

	iov = get_conn_iovec(t, nr_segs);

	if (!iov)

	if (!iov)
@@ -321,9 +322,11 @@ static int ksmbd_tcp_readv(struct tcp_transport *t, struct kvec *iov_orig, 
		} else if (ksmbd_conn_need_reconnect(conn)) {

		} else if (ksmbd_conn_need_reconnect(conn)) {

			total_read = -EAGAIN;

			total_read = -EAGAIN;

			break;

			break;

		} else if (length == -ERESTARTSYS || length == -EAGAIN) {

		} else if ((length == -ERESTARTSYS || length == -EAGAIN) &&

			   max_retry) {

			usleep_range(1000, 2000);

			usleep_range(1000, 2000);

			length = 0;

			length = 0;

			max_retry--;

			continue;

			continue;

		} else if (length <= 0) {

		} else if (length <= 0) {

			total_read = -EAGAIN;

			total_read = -EAGAIN;