linux-kernel - [PATCH] net: qrtr: fix OOB Read in qrtr_endpoint

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Message-Id: <20210614120650.2731-1-paskripkin@gmail.com>
Date:   Mon, 14 Jun 2021 15:06:50 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     mani@...nel.org, davem@...emloft.net, bjorn.andersson@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Pavel Skripkin <paskripkin@...il.com>,
        syzbot+1917d778024161609247@...kaller.appspotmail.com
Subject: [PATCH] net: qrtr: fix OOB Read in qrtr_endpoint_post

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@...kaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---
 net/qrtr/qrtr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index c0477bec09bd..f2efaa4225f9 100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -436,7 +436,7 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
 	struct qrtr_sock *ipc;
 	struct sk_buff *skb;
 	struct qrtr_cb *cb;
-	unsigned int size;
+	size_t size;
 	unsigned int ver;
 	size_t hdrlen;
 
-- 
2.32.0