net: qrtr: fix OOB Read in qrtr_endpoint_post

[ Upstream commit ad9d24c9429e2159d1e279dc3a83191ccb4daf1d ]

Syzbot reported slab-out-of-bounds Read in
qrtr_endpoint_post. The problem was in wrong
_size_ type:

	if (len != ALIGN(size, 4) + hdrlen)
		goto err;

If size from qrtr_hdr is 4294967293 (0xfffffffd), the result of
ALIGN(size, 4) will be 0. In case of len == hdrlen and size == 4294967293
in header this check won't fail and

	skb_put_data(skb, data + hdrlen, size);

will read out of bound from data, which is hdrlen allocated block.

Fixes: 194ccc88297a ("net: qrtr: Support decoding incoming v2 packets")
Reported-and-tested-by: syzbot+1917d778024161609247@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index 46273a8383615411a53003cf46ac069eb96f62a8..faea2ce125110fc27341867f219a0d8ca79fa466 100644 (file)
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -257,7 +257,7 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
        const struct qrtr_hdr_v2 *v2;
        struct sk_buff *skb;
        struct qrtr_cb *cb;
-       unsigned int size;
+       size_t size;
        unsigned int ver;
        size_t hdrlen;