[PATCH 209/379][SRU][OEM-5.6] net: qrtr: Fix an out of bounds read qrtr_endpoint_post()

[You-Sheng Yang]

From: Dan Carpenter <dan.carpenter at oracle.com>

BugLink: https://bugs.launchpad.net/bugs/1879633

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 at linaro.org>
Reported-by: syzbot+b8fe393f999a291a9ea6 at syzkaller.appspotmail.com
Fixes: 194ccc88297a ("net: qrtr: Support decoding incoming v2 packets")
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit 8ff41cc21714704ef0158a546c3c4d07fae2c952)
Signed-off-by: You-Sheng Yang <vicamo.yang at canonical.com>
---
 net/qrtr/qrtr.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index 059881330788..24a8c3c6da0d 100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -429,7 +429,7 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
 	unsigned int ver;
 	size_t hdrlen;
 
-	if (len & 3)
+	if (len == 0 || len & 3)
 		return -EINVAL;
 
 	skb = netdev_alloc_skb(NULL, len);
@@ -443,6 +443,8 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
 
 	switch (ver) {
 	case QRTR_PROTO_VER_1:
+		if (len < sizeof(*v1))
+			goto err;
 		v1 = data;
 		hdrlen = sizeof(*v1);
 
@@ -456,6 +458,8 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
 		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;
 
-- 
2.29.2