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76c67fcc66
This fixes a security problem in ksmbd. It currently has the ZDI-CAN-18259 ID assigned, but no CVE yet. Backported from:8824b7af40cc4f3b5a6aSigned-off-by: Hauke Mehrtens <hauke@hauke-m.de>
64 lines
2.2 KiB
Diff
64 lines
2.2 KiB
Diff
From cc4f3b5a6ab4693aba94a45cc073188df4d67175 Mon Sep 17 00:00:00 2001
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From: Namjae Jeon <linkinjeon@kernel.org>
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Date: Mon, 26 Dec 2022 01:28:52 +0900
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Subject: ksmbd: fix infinite loop in ksmbd_conn_handler_loop()
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If kernel_recvmsg() return -EAGAIN in ksmbd_tcp_readv() and go round
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again, It will cause infinite loop issue. And all threads from next
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connections would be doing that. This patch add max retry count(2) to
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avoid it. kernel_recvmsg() will wait during 7sec timeout and try to
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retry two time if -EAGAIN is returned. And add flags of kvmalloc to
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__GFP_NOWARN and __GFP_NORETRY to disconnect immediately without
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retrying on memory alloation failure.
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Fixes: 0626e66 ("cifsd: add server handler for central processing and tranport layers")
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Cc: stable@vger.kernel.org
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Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-18259
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Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
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Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
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---
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connection.c | 7 +++++--
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transport_tcp.c | 5 ++++-
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2 files changed, 9 insertions(+), 3 deletions(-)
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--- a/connection.c
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+++ b/connection.c
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@@ -337,9 +337,12 @@ int ksmbd_conn_handler_loop(void *p)
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/* 4 for rfc1002 length field */
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size = pdu_size + 4;
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- conn->request_buf = kvmalloc(size, GFP_KERNEL);
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+ conn->request_buf = kvmalloc(size,
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+ GFP_KERNEL |
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+ __GFP_NOWARN |
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+ __GFP_NORETRY);
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if (!conn->request_buf)
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- continue;
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+ break;
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memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf));
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if (!ksmbd_smb_request(conn))
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--- a/transport_tcp.c
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+++ b/transport_tcp.c
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@@ -323,6 +323,7 @@ static int ksmbd_tcp_readv(struct tcp_tr
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struct msghdr ksmbd_msg;
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struct kvec *iov;
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struct ksmbd_conn *conn = KSMBD_TRANS(t)->conn;
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+ int max_retry = 2;
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iov = get_conn_iovec(t, nr_segs);
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if (!iov)
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@@ -349,9 +350,11 @@ static int ksmbd_tcp_readv(struct tcp_tr
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} else if (conn->status == KSMBD_SESS_NEED_RECONNECT) {
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total_read = -EAGAIN;
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break;
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- } else if (length == -ERESTARTSYS || length == -EAGAIN) {
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+ } else if ((length == -ERESTARTSYS || length == -EAGAIN) &&
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+ max_retry) {
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usleep_range(1000, 2000);
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length = 0;
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+ max_retry--;
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continue;
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} else if (length <= 0) {
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total_read = -EAGAIN;
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