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From: Namjae Jeon <linkinjeon@kernel.org>
To: linux-cifs@vger.kernel.org
Cc: "Namjae Jeon" <linkinjeon@kernel.org>,
	"Ronnie Sahlberg" <ronniesahlberg@gmail.com>,
	"Ralph Böhme" <slow@samba.org>,
	"Steve French" <smfrench@gmail.com>,
	"Ronnie Sahlberg" <lsahlber@redhat.com>
Subject: [PATCH v2 3/3] ksmbd: fix invalid request buffer access in compound request
Date: Wed, 22 Sep 2021 07:51:09 +0900	[thread overview]
Message-ID: <20210921225109.6388-3-linkinjeon@kernel.org> (raw)
In-Reply-To: <20210921225109.6388-1-linkinjeon@kernel.org>

Ronnie reported invalid request buffer access in chained command when
inserting garbage value to NextCommand of compound request.
This patch add validation check to avoid this issue.

Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Ralph Böhme <slow@samba.org>
Cc: Steve French <smfrench@gmail.com>
Reported-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 v2:
  - fix integer overflow from work->next_smb2_rcv_hdr_off.

 fs/ksmbd/smb2pdu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 1fe37ad4e5bc..cae796ea1148 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -466,6 +466,13 @@ bool is_chained_smb2_message(struct ksmbd_work *work)
 
 	hdr = ksmbd_req_buf_next(work);
 	if (le32_to_cpu(hdr->NextCommand) > 0) {
+		if ((u64)work->next_smb2_rcv_hdr_off + le32_to_cpu(hdr->NextCommand) >
+		    get_rfc1002_len(work->request_buf)) {
+			pr_err("next command(%u) offset exceeds smb msg size\n",
+			       hdr->NextCommand);
+			return false;
+		}
+
 		ksmbd_debug(SMB, "got SMB2 chained command\n");
 		init_chained_smb2_rsp(work);
 		return true;
-- 
2.25.1


  parent reply	other threads:[~2021-09-21 22:51 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-21 22:51 [PATCH v2 1/3] ksmbd: remove RFC1002 check in smb2 request Namjae Jeon
2021-09-21 22:51 ` [PATCH v2 2/3] ksmbd: add validation in smb2 negotiate Namjae Jeon
2021-09-22 14:17   ` Ralph Boehme
2021-09-22 23:13     ` Namjae Jeon
2021-09-23  0:12       ` ronnie sahlberg
2021-09-23  0:25         ` Namjae Jeon
2021-09-21 22:51 ` Namjae Jeon [this message]
2021-09-22  0:39   ` [PATCH v2 3/3] ksmbd: fix invalid request buffer access in compound request ronnie sahlberg
2021-09-22  4:35     ` Namjae Jeon
2021-09-22  4:56       ` ronnie sahlberg
2021-09-22  5:35         ` Namjae Jeon

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