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    Subject[PATCH AUTOSEL 4.18 092/136] rndis_wlan: potential buffer overflow in rndis_wlan_auth_indication()
    Date
    From: Dan Carpenter <dan.carpenter@oracle.com>

    [ Upstream commit ae636fb1554833ee5133ca47bf4b2791b6739c52 ]

    This is a static checker fix, not something I have tested. The issue
    is that on the second iteration through the loop, we jump forward by
    le32_to_cpu(auth_req->length) bytes. The problem is that if the length
    is more than "buflen" then we end up with a negative "buflen". A
    negative buflen is type promoted to a high positive value and the loop
    continues but it's accessing beyond the end of the buffer.

    I believe the "auth_req->length" comes from the firmware and if the
    firmware is malicious or buggy, you're already toasted so the impact of
    this bug is probably not very severe.

    Fixes: 030645aceb3d ("rndis_wlan: handle 802.11 indications from device")
    Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
    Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    ---
    drivers/net/wireless/rndis_wlan.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/drivers/net/wireless/rndis_wlan.c b/drivers/net/wireless/rndis_wlan.c
    index 9935bd09db1f..d4947e3a909e 100644
    --- a/drivers/net/wireless/rndis_wlan.c
    +++ b/drivers/net/wireless/rndis_wlan.c
    @@ -2928,6 +2928,8 @@ static void rndis_wlan_auth_indication(struct usbnet *usbdev,

    while (buflen >= sizeof(*auth_req)) {
    auth_req = (void *)buf;
    + if (buflen < le32_to_cpu(auth_req->length))
    + return;
    type = "unknown";
    flags = le32_to_cpu(auth_req->flags);
    pairwise_error = false;
    --
    2.17.1
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