linux-kernel - [PATCH RFC 17/33] Input: synaptics-rmi4 - fix a locking bug in an error path

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Message-ID: <20250206175114.1974171-18-bvanassche@acm.org>
Date: Thu,  6 Feb 2025 09:50:58 -0800
From: Bart Van Assche <bvanassche@....org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will@...nel.org>,
	Christoph Hellwig <hch@....de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Marco Elver <elver@...gle.com>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Nathan Chancellor <nathan@...nel.org>,
	Kees Cook <kees@...nel.org>,
	Jann Horn <jannh@...gle.com>,
	linux-kernel@...r.kernel.org,
	Bart Van Assche <bvanassche@....org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Nick Dyer <nick@...anahar.org>
Subject: [PATCH RFC 17/33] Input: synaptics-rmi4 - fix a locking bug in an error path

Lock f54->data_mutex before the first 'goto error' statement since
jumping to the 'error' label causes that mutex to be unlocked.

Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Nick Dyer <nick@...anahar.org>
Fixes: 3a762dbd5347 ("[media] Input: synaptics-rmi4 - add support for F54 diagnostics")
Signed-off-by: Bart Van Assche <bvanassche@....org>
---
 drivers/input/rmi4/rmi_f54.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/input/rmi4/rmi_f54.c b/drivers/input/rmi4/rmi_f54.c
index 5c3da910b5b2..f7387527e8b3 100644
--- a/drivers/input/rmi4/rmi_f54.c
+++ b/drivers/input/rmi4/rmi_f54.c
@@ -541,6 +541,9 @@ static void rmi_f54_work(struct work_struct *work)
 	int i;
 
 	report_size = rmi_f54_get_report_size(f54);
+
+	mutex_lock(&f54->data_mutex);
+
 	if (report_size == 0) {
 		dev_err(&fn->dev, "Bad report size, report type=%d\n",
 				f54->report_type);
@@ -548,8 +551,6 @@ static void rmi_f54_work(struct work_struct *work)
 		goto error;     /* retry won't help */
 	}
 
-	mutex_lock(&f54->data_mutex);
-
 	/*
 	 * Need to check if command has completed.
 	 * If not try again later.