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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        syzbot+b8fe393f999a291a9ea6@syzkaller.appspotmail.com,
        Dan Carpenter <dan.carpenter@oracle.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.4 035/109] net: qrtr: Fix an out of bounds read qrtr_endpoint_post()
Date:   Tue, 14 Jul 2020 20:43:38 +0200
Message-Id: <20200714184107.201437055@linuxfoundation.org>
In-Reply-To: <20200714184105.507384017@linuxfoundation.org>
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From: Dan Carpenter <dan.carpenter@oracle.com>

commit 8ff41cc21714704ef0158a546c3c4d07fae2c952 upstream.

This code assumes that the user passed in enough data for a
qrtr_hdr_v1 or qrtr_hdr_v2 struct, but it's not necessarily true.  If
the buffer is too small then it will read beyond the end.

Reported-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reported-by: syzbot+b8fe393f999a291a9ea6@syzkaller.appspotmail.com
Fixes: 194ccc88297a ("net: qrtr: Support decoding incoming v2 packets")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/qrtr/qrtr.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -259,7 +259,7 @@ int qrtr_endpoint_post(struct qrtr_endpo
 	unsigned int ver;
 	size_t hdrlen;
 
-	if (len & 3)
+	if (len == 0 || len & 3)
 		return -EINVAL;
 
 	skb = netdev_alloc_skb(NULL, len);
@@ -273,6 +273,8 @@ int qrtr_endpoint_post(struct qrtr_endpo
 
 	switch (ver) {
 	case QRTR_PROTO_VER_1:
+		if (len < sizeof(*v1))
+			goto err;
 		v1 = data;
 		hdrlen = sizeof(*v1);
 
@@ -286,6 +288,8 @@ int qrtr_endpoint_post(struct qrtr_endpo
 		size = le32_to_cpu(v1->size);
 		break;
 	case QRTR_PROTO_VER_2:
+		if (len < sizeof(*v2))
+			goto err;
 		v2 = data;
 		hdrlen = sizeof(*v2) + v2->optlen;