[PATCH 5.12 061/178] net: qrtr: fix OOB Read in qrtr_endpoint_post

Greg Kroah-Hartman
2021-06-21T16:45:40Z

From: Pavel Skripkin <paskripkin@gmail.com>

[ 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>
---
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 1e4fb568fa84..24f10bf7d8a3 100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -435,7 +435,7 @@ 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;

--
2.30.2