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FAILED: patch "[PATCH] Input: synaptics - fix crash when enabling pass-through port" failed to apply to 6.12-stable tree

PATCH [email protected] 1 participant 1 message Feb 10, 2025

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The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 08bd5b7c9a2401faabdaa1472d45c7de0755fd7e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025021059-splice-blush-823b@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 08bd5b7c9a2401faabdaa1472d45c7de0755fd7e Mon Sep 17 00:00:00 2001
From: Dmitry Torokhov <[email protected]>
Date: Fri, 17 Jan 2025 09:23:40 -0800
Subject: [PATCH] Input: synaptics - fix crash when enabling pass-through port

When enabling a pass-through port an interrupt might come before psmouse driver binds to the pass-through port. However synaptics sub-driver tries to access psmouse instance presumably associated with the pass-through port to figure out if only 1 byte of response or entire protocol packet needs to be forwarded to the pass-through port and may crash if psmouse instance has not been attached to the port yet.

Fix the crash by introducing open() and close() methods for the port and check if the port is open before trying to access psmouse instance. Because psmouse calls serio_open() only after attaching psmouse instance to serio port instance this prevents the potential crash.

Reported-by Takashi Iwai <[email protected]>
Fixes 100e16959c3c ("Input: libps2 - attach ps2dev instances as serio port's drvdata")
Link https://bugzilla.suse.com/show_bug.cgi?id=1219522
Cc [email protected]
Reviewed-by Takashi Iwai <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Dmitry Torokhov <[email protected]>
drivers/input/mouse/synaptics.c +42 -14
index 2735f86c23cc..aba57abe6978 100644
@@ -665,23 +665,50 @@ static void synaptics_pt_stop(struct serio *serio)
 	priv->pt_port = NULL;
 }
 
+static int synaptics_pt_open(struct serio *serio)
+{
+	struct psmouse *parent = psmouse_from_serio(serio->parent);
+	struct synaptics_data *priv = parent->private;
+
+	guard(serio_pause_rx)(parent->ps2dev.serio);
+	priv->pt_port_open = true;
+
+	return 0;
+}
+
+static void synaptics_pt_close(struct serio *serio)
+{
+	struct psmouse *parent = psmouse_from_serio(serio->parent);
+	struct synaptics_data *priv = parent->private;
+
+	guard(serio_pause_rx)(parent->ps2dev.serio);
+	priv->pt_port_open = false;
+}
+
 static int synaptics_is_pt_packet(u8 *buf)
 {
 	return (buf[0] & 0xFC) == 0x84 && (buf[3] & 0xCC) == 0xC4;
 }
 
-static void synaptics_pass_pt_packet(struct serio *ptport, u8 *packet)
+static void synaptics_pass_pt_packet(struct synaptics_data *priv, u8 *packet)
 {
-	struct psmouse *child = psmouse_from_serio(ptport);
+	struct serio *ptport;
 
-	if (child && child->state == PSMOUSE_ACTIVATED) {
-		serio_interrupt(ptport, packet[1], 0);
-		serio_interrupt(ptport, packet[4], 0);
-		serio_interrupt(ptport, packet[5], 0);
-		if (child->pktsize == 4)
-			serio_interrupt(ptport, packet[2], 0);
-	} else {
-		serio_interrupt(ptport, packet[1], 0);
+	ptport = priv->pt_port;
+	if (!ptport)
+		return;
+
+	serio_interrupt(ptport, packet[1], 0);
+
+	if (priv->pt_port_open) {
+		struct psmouse *child = psmouse_from_serio(ptport);
+
+		if (child->state == PSMOUSE_ACTIVATED) {
+			serio_interrupt(ptport, packet[4], 0);
+			serio_interrupt(ptport, packet[5], 0);
+			if (child->pktsize == 4)
+				serio_interrupt(ptport, packet[2], 0);
+		}
 	}
 }
 

@@ -720,6 +747,8 @@ static void synaptics_pt_create(struct psmouse *psmouse)
 	serio->write = synaptics_pt_write;
 	serio->start = synaptics_pt_start;
 	serio->stop = synaptics_pt_stop;
+	serio->open = synaptics_pt_open;
+	serio->close = synaptics_pt_close;
 	serio->parent = psmouse->ps2dev.serio;
 
 	psmouse->pt_activate = synaptics_pt_activate;

@@ -1216,11 +1245,10 @@ static psmouse_ret_t synaptics_process_byte(struct psmouse *psmouse)
 
 		if (SYN_CAP_PASS_THROUGH(priv->info.capabilities) &&
 		    synaptics_is_pt_packet(psmouse->packet)) {
-			if (priv->pt_port)
-				synaptics_pass_pt_packet(priv->pt_port,
-							 psmouse->packet);
-		} else
+			synaptics_pass_pt_packet(priv, psmouse->packet);
+		} else {
 			synaptics_process_packet(psmouse);
+		}
 
 		return PSMOUSE_FULL_PACKET;
 	}
drivers/input/mouse/synaptics.h +1 -0
index 899aee598632..3853165b6b3a 100644
@@ -188,6 +188,7 @@ struct synaptics_data {
 	bool disable_gesture;			/* disable gestures */
 
 	struct serio *pt_port;			/* Pass-through serio port */
+	bool pt_port_open;
 
 	/*
 	 * Last received Advanced Gesture Mode (AGM) packet. An AGM packet