From f89f46cf3a23d8d7c98f924a461fd931e1331746 Mon Sep 17 00:00:00 2001 From: Luciano Coelho Date: Mon, 1 Dec 2014 11:32:09 +0200 Subject: [PATCH] nl80211: check matches array length before acessing it If the userspace passes a malformed sched scan request (or a net detect wowlan configuration) by adding a NL80211_ATTR_SCHED_SCAN_MATCH attribute without any nested matchsets, a NULL pointer dereference will occur. Fix this by checking that we do have matchsets in our array before trying to access it. BUG: unable to handle kernel NULL pointer dereference at 0000000000000024 IP: [] nl80211_parse_sched_scan.part.67+0x6e9/0x900 [cfg80211] PGD 865c067 PUD 865b067 PMD 0 Oops: 0002 [#1] SMP Modules linked in: iwlmvm(O) iwlwifi(O) mac80211(O) cfg80211(O) compat(O) [last unloaded: compat] CPU: 2 PID: 2442 Comm: iw Tainted: G O 3.17.2 #31 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 task: ffff880013800790 ti: ffff880008d80000 task.ti: ffff880008d80000 RIP: 0010:[] [] nl80211_parse_sched_scan.part.67+0x6e9/0x900 [cfg80211] RSP: 0018:ffff880008d838d0 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 000000000000143c RSI: 0000000000000000 RDI: ffff880008ee8dd0 RBP: ffff880008d83948 R08: 0000000000000002 R09: 0000000000000019 R10: ffff88001d1b3c40 R11: 0000000000000002 R12: ffff880019e85e00 R13: 00000000fffffed4 R14: ffff880009757800 R15: 0000000000001388 FS: 00007fa3b6d13700(0000) GS:ffff88003e200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000024 CR3: 0000000008670000 CR4: 00000000000006e0 Stack: ffff880009757800 ffff880000000001 0000000000000000 ffff880008ee84e0 0000000000000000 ffff880009757800 00000000fffffed4 ffff880008d83948 ffffffff814689c9 ffff880009757800 ffff880008ee8000 0000000000000000 Call Trace: [] ? nla_parse+0xb9/0x120 [] nl80211_set_wowlan+0x75e/0x960 [cfg80211] [] ? mark_held_locks+0x75/0xa0 [] genl_family_rcv_msg+0x18b/0x360 [] ? trace_hardirqs_on+0xd/0x10 [] genl_rcv_msg+0x84/0xc0 [] ? genl_family_rcv_msg+0x360/0x360 [] netlink_rcv_skb+0xa9/0xd0 [] genl_rcv+0x28/0x40 [] netlink_unicast+0x105/0x180 [] netlink_sendmsg+0x34f/0x7a0 [] ? kvm_clock_read+0x27/0x40 [] sock_sendmsg+0x8d/0xc0 [] ? might_fault+0xb9/0xc0 [] ? might_fault+0x5e/0xc0 [] ? verify_iovec+0x56/0xe0 [] ___sys_sendmsg+0x3d0/0x3e0 [] ? sched_clock_cpu+0x98/0xd0 [] ? __do_page_fault+0x254/0x580 [] ? up_read+0x1f/0x40 [] ? __do_page_fault+0x254/0x580 [] ? __fget_light+0x13d/0x160 [] __sys_sendmsg+0x42/0x80 [] SyS_sendmsg+0x12/0x20 [] system_call_fastpath+0x16/0x1b Fixes: ea73cbce4e1f ("nl80211: fix scheduled scan RSSI matchset attribute confusion") Cc: stable@vger.kernel.org [3.15+] Signed-off-by: Luciano Coelho Signed-off-by: Johannes Berg --- net/wireless/nl80211.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index a17d6bc..7ca4b51 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -6002,7 +6002,7 @@ nl80211_parse_sched_scan(struct wiphy *wiphy, struct wireless_dev *wdev, } /* there was no other matchset, so the RSSI one is alone */ - if (i == 0) + if (i == 0 && n_match_sets) request->match_sets[0].rssi_thold = default_match_rssi; request->min_rssi_thold = INT_MAX; -- 2.7.4