FAILED: patch "[PATCH] Input: mms114 - reject an oversized device packet size" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 66725039f7090afe14c31bd259e2059a68f04023
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026071645-latch-matchless-9242@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 66725039f7090afe14c31bd259e2059a68f04023 Mon Sep 17 00:00:00 2001
From: Bryam Vargas <[email protected]>
Date: Sun, 14 Jun 2026 14:19:43 -0700
Subject: [PATCH] Input: mms114 - reject an oversized device packet size

mms114_interrupt() reads a packet of touch data from the device into a fixed-size on-stack buffer

	struct mms114_touch touch[MMS114_MAX_TOUCH];

which holds MMS114_MAX_TOUCH (10) events of MMS114_EVENT_SIZE (8) bytes, i.e. 80 bytes. The length of the I2C read into it is taken verbatim from the device:

	packet_size = mms114_read_reg(data, MMS114_PACKET_SIZE);
	if (packet_size <= 0)
		goto out;
	...
	error = __mms114_read_reg(data, MMS114_INFORMATION, packet_size,
			(u8 *)touch);

packet_size is a single device register byte (0x0F) and the only check is the lower bound packet_size <= 0; it is never bounded against the size of touch[]. A malfunctioning, malicious or counterfeit controller (or an attacker tampering with the I2C bus) can report a packet_size of up to 255, so __mms114_read_reg() writes up to 175 bytes past the end of touch[] on the IRQ-thread stack: a stack out-of-bounds write that can overwrite the stack canary, saved registers and the return address.

A well-formed device never reports more than the buffer holds, so reject an oversized packet and drop the report, consistent with the handler's other error paths, rather than reading past the buffer.

index 9597214d9d3c..4d748a13408d 100644
@@ -226,6 +226,12 @@ static irqreturn_t mms114_interrupt(int irq, void *dev_id)
 	if (packet_size <= 0)
 		goto out;
 
+	if (packet_size > sizeof(touch)) {
+		dev_err(&client->dev, "Invalid packet size %d (max %zu)\n",
+			packet_size, sizeof(touch));
+		goto out;
+	}
+
 	/* MMS136 has slightly different event size */
 	if (data->type == TYPE_MMS134S || data->type == TYPE_MMS136)
 		touch_size = packet_size / MMS136_EVENT_SIZE;

From: Bryam Vargas <[email protected]>

[ Upstream commit 66725039f7090afe14c31bd259e2059a68f04023 ]

mms114_interrupt() reads a packet of touch data from the device into a fixed-size on-stack buffer

	struct mms114_touch touch[MMS114_MAX_TOUCH];

which holds MMS114_MAX_TOUCH (10) events of MMS114_EVENT_SIZE (8) bytes, i.e. 80 bytes. The length of the I2C read into it is taken verbatim from the device:

	packet_size = mms114_read_reg(data, MMS114_PACKET_SIZE);
	if (packet_size <= 0)
		goto out;
	...
	error = __mms114_read_reg(data, MMS114_INFORMATION, packet_size,
			(u8 *)touch);

packet_size is a single device register byte (0x0F) and the only check is the lower bound packet_size <= 0; it is never bounded against the size of touch[]. A malfunctioning, malicious or counterfeit controller (or an attacker tampering with the I2C bus) can report a packet_size of up to 255, so __mms114_read_reg() writes up to 175 bytes past the end of touch[] on the IRQ-thread stack: a stack out-of-bounds write that can overwrite the stack canary, saved registers and the return address.

A well-formed device never reports more than the buffer holds, so reject an oversized packet and drop the report, consistent with the handler's other error paths, rather than reading past the buffer.

---
 drivers/input/touchscreen/mms114.c | 6 ++++++
 1 file changed, 6 insertions(+)

index 9fa3b0e421be2a..566a95ab0cc347 100644
@@ -212,6 +212,12 @@ static irqreturn_t mms114_interrupt(int irq, void *dev_id)
 	if (packet_size <= 0)
 		goto out;
 
+	if (packet_size > sizeof(touch)) {
+		dev_err(&data->client->dev, "Invalid packet size %d (max %zu)\n",
+			packet_size, sizeof(touch));
+		goto out;
+	}
+
 	/* MMS136 has slightly different event size */
 	if (data->type == TYPE_MMS134S || data->type == TYPE_MMS136)
 		touch_size = packet_size / MMS136_EVENT_SIZE;

2.53.0

From: Bryam Vargas <[email protected]>

[ Upstream commit 66725039f7090afe14c31bd259e2059a68f04023 ]

mms114_interrupt() reads a packet of touch data from the device into a fixed-size on-stack buffer

	struct mms114_touch touch[MMS114_MAX_TOUCH];

which holds MMS114_MAX_TOUCH (10) events of MMS114_EVENT_SIZE (8) bytes, i.e. 80 bytes. The length of the I2C read into it is taken verbatim from the device:

	packet_size = mms114_read_reg(data, MMS114_PACKET_SIZE);
	if (packet_size <= 0)
		goto out;
	...
	error = __mms114_read_reg(data, MMS114_INFORMATION, packet_size,
			(u8 *)touch);

packet_size is a single device register byte (0x0F) and the only check is the lower bound packet_size <= 0; it is never bounded against the size of touch[]. A malfunctioning, malicious or counterfeit controller (or an attacker tampering with the I2C bus) can report a packet_size of up to 255, so __mms114_read_reg() writes up to 175 bytes past the end of touch[] on the IRQ-thread stack: a stack out-of-bounds write that can overwrite the stack canary, saved registers and the return address.

A well-formed device never reports more than the buffer holds, so reject an oversized packet and drop the report, consistent with the handler's other error paths, rather than reading past the buffer.

---
 drivers/input/touchscreen/mms114.c | 6 ++++++
 1 file changed, 6 insertions(+)

index 9fa3b0e421be2a..566a95ab0cc347 100644
@@ -212,6 +212,12 @@ static irqreturn_t mms114_interrupt(int irq, void *dev_id)
 	if (packet_size <= 0)
 		goto out;
 
+	if (packet_size > sizeof(touch)) {
+		dev_err(&data->client->dev, "Invalid packet size %d (max %zu)\n",
+			packet_size, sizeof(touch));
+		goto out;
+	}
+
 	/* MMS136 has slightly different event size */
 	if (data->type == TYPE_MMS134S || data->type == TYPE_MMS136)
 		touch_size = packet_size / MMS136_EVENT_SIZE;

2.53.0