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From: Marios Makassikis <mmakassikis@freebox.fr>
To: linux-cifs@vger.kernel.org
Cc: Marios Makassikis <mmakassikis@freebox.fr>
Subject: [PATCH] ksmbd: Fix buffer length check in fsctl_validate_negotiate_info()
Date: Thu, 28 Oct 2021 21:01:27 +0200	[thread overview]
Message-ID: <20211028190125.391374-1-mmakassikis@freebox.fr> (raw)

The validate_negotiate_info_req struct definition includes an extra
field to access the data coming after the header. This causes the check
in fsctl_validate_negotiate_info() to count the first element of the
array twice. This in turn makes some valid requests fail, depending on
whether they include padding or not.

Fixes: f7db8fd03a4b ("ksmbd: add validation in smb2_ioctl")
Signed-off-by: Marios Makassikis <mmakassikis@freebox.fr>
---
This causes mounts to fail on older kernels (v4.19 on debian10) when
specifying vers=3.0.

 fs/ksmbd/smb2pdu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 7e448df3f847..a03b53df3f04 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -7312,7 +7312,7 @@ static int fsctl_validate_negotiate_info(struct ksmbd_conn *conn,
 	int ret = 0;
 	int dialect;
 
-	if (in_buf_len < sizeof(struct validate_negotiate_info_req) +
+	if (in_buf_len < offsetof(struct validate_negotiate_info_req, Dialects) +
 			le16_to_cpu(neg_req->DialectCount) * sizeof(__le16))
 		return -EINVAL;
 
-- 
2.25.1


             reply	other threads:[~2021-10-28 19:01 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-28 19:01 Marios Makassikis [this message]
2021-10-28 22:41 ` [PATCH] ksmbd: Fix buffer length check in fsctl_validate_negotiate_info() Namjae Jeon
2021-10-28 23:56 ` Hyunchul Lee

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