From 696da02259463ea634821e117088f82afe7bf851 Mon Sep 17 00:00:00 2001 From: Hui Peng Date: Sat, 3 Aug 2019 20:29:04 -0400 Subject: [PATCH] ath6kl: fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from_pipe() [ Upstream commit 39d170b3cb62ba98567f5c4f40c27b5864b304e5 ] The `ar_usb` field of `ath6kl_usb_pipe_usb_pipe` objects are initialized to point to the containing `ath6kl_usb` object according to endpoint descriptors read from the device side, as shown below in `ath6kl_usb_setup_pipe_resources`: for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) { endpoint = &iface_desc->endpoint[i].desc; // get the address from endpoint descriptor pipe_num = ath6kl_usb_get_logical_pipe_num(ar_usb, endpoint->bEndpointAddress, &urbcount); ...... // select the pipe object pipe = &ar_usb->pipes[pipe_num]; // initialize the ar_usb field pipe->ar_usb = ar_usb; } The driver assumes that the addresses reported in endpoint descriptors from device side to be complete. If a device is malicious and does not report complete addresses, it may trigger NULL-ptr-deref `ath6kl_usb_alloc_urb_from_pipe` and `ath6kl_usb_free_urb_to_pipe`. This patch fixes the bug by preventing potential NULL-ptr-deref (CVE-2019-15098). Signed-off-by: Hui Peng Reported-by: Hui Peng Reported-by: Mathias Payer Reviewed-by: Greg Kroah-Hartman Signed-off-by: Kalle Valo Signed-off-by: Sasha Levin --- drivers/net/wireless/ath/ath6kl/usb.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c index 4defb7a..53b66e9 100644 --- a/drivers/net/wireless/ath/ath6kl/usb.c +++ b/drivers/net/wireless/ath/ath6kl/usb.c @@ -132,6 +132,10 @@ ath6kl_usb_alloc_urb_from_pipe(struct ath6kl_usb_pipe *pipe) struct ath6kl_urb_context *urb_context = NULL; unsigned long flags; + /* bail if this pipe is not initialized */ + if (!pipe->ar_usb) + return NULL; + spin_lock_irqsave(&pipe->ar_usb->cs_lock, flags); if (!list_empty(&pipe->urb_list_head)) { urb_context = @@ -150,6 +154,10 @@ static void ath6kl_usb_free_urb_to_pipe(struct ath6kl_usb_pipe *pipe, { unsigned long flags; + /* bail if this pipe is not initialized */ + if (!pipe->ar_usb) + return; + spin_lock_irqsave(&pipe->ar_usb->cs_lock, flags); pipe->urb_cnt++; -- 2.7.4