[openwrt/openwrt] hostapd: P2P: Fix a corner case in peer addition based on PD Request

[LEDE Commits]

hauke pushed a commit to openwrt/openwrt.git, branch openwrt-21.02:
https://git.openwrt.org/7b6ee74ee9455c068981cba2feb97538062389aa

commit 7b6ee74ee9455c068981cba2feb97538062389aa
Author: Stefan Lippers-Hollmann <s.l-h at gmx.de>
AuthorDate: Sat Feb 27 23:55:08 2021 +0100

    hostapd: P2P: Fix a corner case in peer addition based on PD Request
    
    p2p_add_device() may remove the oldest entry if there is no room in the
    peer table for a new peer. This would result in any pointer to that
    removed entry becoming stale. A corner case with an invalid PD Request
    frame could result in such a case ending up using (read+write) freed
    memory. This could only by triggered when the peer table has reached its
    maximum size and the PD Request frame is received from the P2P Device
    Address of the oldest remaining entry and the frame has incorrect P2P
    Device Address in the payload.
    
    Fix this by fetching the dev pointer again after having called
    p2p_add_device() so that the stale pointer cannot be used.
    
    This fixes the following security vulnerabilities/bugs:
    
    - CVE-2021-27803 - A vulnerability was discovered in how p2p/p2p_pd.c
      in wpa_supplicant before 2.10 processes P2P (Wi-Fi Direct) provision
      discovery requests. It could result in denial of service or other
      impact (potentially execution of arbitrary code), for an attacker
      within radio range.
    
    Fixes: 17bef1e97a50 ("P2P: Add peer entry based on Provision Discovery Request")
    Signed-off-by: Jouni Malinen <jouni at codeaurora.org>
    Signed-off-by: Stefan Lippers-Hollmann <s.l-h at gmx.de>
    (cherry picked from commit 1ca5de13a153061feae260864d73d96f7c463785)
---
 ...orner-case-in-peer-addition-based-on-PD-R.patch | 45 ++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/package/network/services/hostapd/patches/060-P2P-Fix-a-corner-case-in-peer-addition-based-on-PD-R.patch b/package/network/services/hostapd/patches/060-P2P-Fix-a-corner-case-in-peer-addition-based-on-PD-R.patch
new file mode 100644
index 0000000000..1202ff3725
--- /dev/null
+++ b/package/network/services/hostapd/patches/060-P2P-Fix-a-corner-case-in-peer-addition-based-on-PD-R.patch
@@ -0,0 +1,45 @@
+From 8460e3230988ef2ec13ce6b69b687e941f6cdb32 Mon Sep 17 00:00:00 2001
+From: Jouni Malinen <jouni at codeaurora.org>
+Date: Tue, 8 Dec 2020 23:52:50 +0200
+Subject: [PATCH] P2P: Fix a corner case in peer addition based on PD Request
+
+p2p_add_device() may remove the oldest entry if there is no room in the
+peer table for a new peer. This would result in any pointer to that
+removed entry becoming stale. A corner case with an invalid PD Request
+frame could result in such a case ending up using (read+write) freed
+memory. This could only by triggered when the peer table has reached its
+maximum size and the PD Request frame is received from the P2P Device
+Address of the oldest remaining entry and the frame has incorrect P2P
+Device Address in the payload.
+
+Fix this by fetching the dev pointer again after having called
+p2p_add_device() so that the stale pointer cannot be used.
+
+Fixes: 17bef1e97a50 ("P2P: Add peer entry based on Provision Discovery Request")
+Signed-off-by: Jouni Malinen <jouni at codeaurora.org>
+---
+ src/p2p/p2p_pd.c | 12 +++++-------
+ 1 file changed, 5 insertions(+), 7 deletions(-)
+
+--- a/src/p2p/p2p_pd.c
++++ b/src/p2p/p2p_pd.c
+@@ -595,14 +595,12 @@ void p2p_process_prov_disc_req(struct p2
+ 			goto out;
+ 		}
+ 
++		dev = p2p_get_device(p2p, sa);
+ 		if (!dev) {
+-			dev = p2p_get_device(p2p, sa);
+-			if (!dev) {
+-				p2p_dbg(p2p,
+-					"Provision Discovery device not found "
+-					MACSTR, MAC2STR(sa));
+-				goto out;
+-			}
++			p2p_dbg(p2p,
++				"Provision Discovery device not found "
++				MACSTR, MAC2STR(sa));
++			goto out;
+ 		}
+ 	} else if (msg.wfd_subelems) {
+ 		wpabuf_free(dev->info.wfd_subelems);