netdev - [PATCH 3/3] Bluetooth: Fix kernel crash on L2CAP stress tests

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Date:	Sun, 21 Mar 2010 06:41:37 +0100
From:	Marcel Holtmann <marcel@...tmann.org>
To:	David Miller <davem@...emloft.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	netdev@...r.kernel.org
Subject: [PATCH 3/3] Bluetooth: Fix kernel crash on L2CAP stress tests

From: Andrei Emeltchenko <andrei.emeltchenko@...ia.com>

Added very simple check that req buffer has enough space to
fit configuration parameters. Shall be enough to reject packets
with configuration size more than req buffer.

Crash trace below

[ 6069.659393] Unable to handle kernel paging request at virtual address 02000205
[ 6069.673034] Internal error: Oops: 805 [#1] PREEMPT
...
[ 6069.727172] PC is at l2cap_add_conf_opt+0x70/0xf0 [l2cap]
[ 6069.732604] LR is at l2cap_recv_frame+0x1350/0x2e78 [l2cap]
...
[ 6070.030303] Backtrace:
[ 6070.032806] [<bf1c2880>] (l2cap_add_conf_opt+0x0/0xf0 [l2cap]) from
[<bf1c6624>] (l2cap_recv_frame+0x1350/0x2e78 [l2cap])
[ 6070.043823]  r8:dc5d3100 r7:df2a91d6 r6:00000001 r5:df2a8000 r4:00000200
[ 6070.050659] [<bf1c52d4>] (l2cap_recv_frame+0x0/0x2e78 [l2cap]) from
[<bf1c8408>] (l2cap_recv_acldata+0x2bc/0x350 [l2cap])
[ 6070.061798] [<bf1c814c>] (l2cap_recv_acldata+0x0/0x350 [l2cap]) from
[<bf0037a4>] (hci_rx_task+0x244/0x478 [bluetooth])
[ 6070.072631]  r6:dc647700 r5:00000001 r4:df2ab740
[ 6070.077362] [<bf003560>] (hci_rx_task+0x0/0x478 [bluetooth]) from
[<c006b9fc>] (tasklet_action+0x78/0xd8)
[ 6070.087005] [<c006b984>] (tasklet_action+0x0/0xd8) from [<c006c160>]

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@...ia.com>
Acked-by: Gustavo F. Padovan <gustavo@...ovan.org>
Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
---
 net/bluetooth/l2cap.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index 43e17f7..7794a2e 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -2832,6 +2832,11 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hdr
 			int len = cmd->len - sizeof(*rsp);
 			char req[64];
 
+			if (len > sizeof(req) - sizeof(struct l2cap_conf_req)) {
+				l2cap_send_disconn_req(conn, sk);
+				goto done;
+			}
+
 			/* throw out any old stored conf requests */
 			result = L2CAP_CONF_SUCCESS;
 			len = l2cap_parse_conf_rsp(sk, rsp->data,
-- 
1.6.6.1

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