linux-kernel - [PATCH v2 1/3] dell-laptop: Clear buffer before each SMBIOS call

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Message-Id: <1436177337-13654-1-git-send-email-pali.rohar@gmail.com>
Date:	Mon,  6 Jul 2015 12:08:55 +0200
From:	Pali Rohár <pali.rohar@...il.com>
To:	Darren Hart <dvhart@...radead.org>,
	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	Gabriele Mazzotta <gabriele.mzt@...il.com>,
	Pali Rohár <pali.rohar@...il.com>
Subject: [PATCH v2 1/3] dell-laptop: Clear buffer before each SMBIOS call

Make sure that before initializing SMBIOS call input buffer does not
contain any garbage (e.g. values from previous SMBIOS call). This fix
problem with passing undefined/random parameters to SMBIOS functions.

Signed-off-by: Pali Rohár <pali.rohar@...il.com>
---
 drivers/platform/x86/dell-laptop.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index 35758cb..2caefb2 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -310,10 +310,15 @@ static DEFINE_MUTEX(buffer_mutex);
 
 static int hwswitch_state;
 
+static void clear_buffer(void)
+{
+	memset(buffer, 0, sizeof(struct calling_interface_buffer));
+}
+
 static void get_buffer(void)
 {
 	mutex_lock(&buffer_mutex);
-	memset(buffer, 0, sizeof(struct calling_interface_buffer));
+	clear_buffer();
 }
 
 static void release_buffer(void)
@@ -557,6 +562,8 @@ static int dell_rfkill_set(void *data, bool blocked)
 	    !(buffer->output[1] & BIT(16)))
 		disable = 1;
 
+	clear_buffer();
+
 	buffer->input[0] = (1 | (radio<<8) | (disable << 16));
 	dell_send_request(buffer, 17, 11);
 
@@ -571,6 +578,7 @@ static void dell_rfkill_update_sw_state(struct rfkill *rfkill, int radio,
 	if (status & BIT(0)) {
 		/* Has hw-switch, sync sw_state to BIOS */
 		int block = rfkill_blocked(rfkill);
+		clear_buffer();
 		buffer->input[0] = (1 | (radio << 8) | (block << 16));
 		dell_send_request(buffer, 17, 11);
 	} else {
@@ -773,6 +781,7 @@ static int __init dell_setup_rfkill(void)
 	get_buffer();
 	dell_send_request(buffer, 17, 11);
 	status = buffer->output[1];
+	clear_buffer();
 	buffer->input[0] = 0x2;
 	dell_send_request(buffer, 17, 11);
 	hwswitch_state = buffer->output[1];
-- 
1.7.9.5

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