linux-kernel - [ 42/58] n_gsm: added interlocking for gsm_data

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20121004210640.743182779@linuxfoundation.org>
Date:	Thu,  4 Oct 2012 14:19:49 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk, Russ Gorby <russ.gorby@...el.com>,
	"Yin, Fengwei" <fengwei.yin@...el.com>,
	Alan Cox <alan@...ux.intel.com>
Subject: [ 42/58] n_gsm: added interlocking for gsm_data_lock for certain code paths

3.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Russ Gorby <russ.gorby@...el.com>

commit 5e44708f75b0f8712da715d6babb0c21089b2317 upstream.

There were some locking holes in the management of the MUX's
message queue for 2 code paths:
1) gsmld_write_wakeup
2) receipt of CMD_FCON flow-control message
In both cases gsm_data_kick is called w/o locking so it can collide
with other other instances of gsm_data_kick (pulling messages tx_tail)
or potentially other instances of __gsm_data_queu (adding messages to tx_head)

Changed to take the tx_lock in these 2 cases

Signed-off-by: Russ Gorby <russ.gorby@...el.com>
Tested-by: Yin, Fengwei <fengwei.yin@...el.com>
Signed-off-by: Alan Cox <alan@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/tty/n_gsm.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1193,6 +1193,8 @@ static void gsm_control_message(struct g
 							u8 *data, int clen)
 {
 	u8 buf[1];
+	unsigned long flags;
+
 	switch (command) {
 	case CMD_CLD: {
 		struct gsm_dlci *dlci = gsm->dlci[0];
@@ -1218,7 +1220,9 @@ static void gsm_control_message(struct g
 		gsm->constipated = 0;
 		gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
 		/* Kick the link in case it is idling */
+		spin_lock_irqsave(&gsm->tx_lock, flags);
 		gsm_data_kick(gsm);
+		spin_unlock_irqrestore(&gsm->tx_lock, flags);
 		break;
 	case CMD_MSC:
 		/* Out of band modem line change indicator for a DLCI */
@@ -2380,12 +2384,12 @@ static void gsmld_write_wakeup(struct tt
 
 	/* Queue poll */
 	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+	spin_lock_irqsave(&gsm->tx_lock, flags);
 	gsm_data_kick(gsm);
 	if (gsm->tx_bytes < TX_THRESH_LO) {
-		spin_lock_irqsave(&gsm->tx_lock, flags);
 		gsm_dlci_data_sweep(gsm);
-		spin_unlock_irqrestore(&gsm->tx_lock, flags);
 	}
+	spin_unlock_irqrestore(&gsm->tx_lock, flags);
 }
 
 /**


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/