linux-kernel - [PATCH] acer-wmi: fix memory leaks in wmab

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Message-Id: <1278647475.26099.2.camel@mola>
Date:	Fri, 09 Jul 2010 11:51:15 +0800
From:	Axel Lin <axel.lin@...il.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	Carlos Corbacho <carlos@...angeworlds.co.uk>,
	Matthew Garrett <mjg@...hat.com>,
	Thomas Renninger <trenn@...e.de>,
	Alan Jenkins <alan-jenkins@...fmail.co.uk>,
	platform-driver-x86@...r.kernel.org
Subject: [PATCH] acer-wmi: fix memory leaks in wmab_execute error path

When acpi_evaluate_object() is passed ACPI_ALLOCATE_BUFFER,
the caller must kfree the returned buffer if AE_OK is returned.

Call Trace:
wmab_execute
  -> wmi_evaluate_method
    -> acpi_evaluate_object

Thus if callers of wmab_execute() pass ACPI_ALLOCATE_BUFFER,
the return buffer must be kfreed if wmab_execute return AE_OK.

Signed-off-by: Axel Lin <axel.lin@...il.com>
---
 drivers/platform/x86/acer-wmi.c |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
index 1ea6c43..a158d39 100644
--- a/drivers/platform/x86/acer-wmi.c
+++ b/drivers/platform/x86/acer-wmi.c
@@ -555,6 +555,7 @@ static acpi_status AMW0_find_mailled(void)
 	obj->buffer.length == sizeof(struct wmab_ret)) {
 		ret = *((struct wmab_ret *) obj->buffer.pointer);
 	} else {
+		kfree(out.pointer);
 		return AE_ERROR;
 	}
 
@@ -598,6 +599,7 @@ static acpi_status AMW0_set_capabilities(void)
 	obj->buffer.length == sizeof(struct wmab_ret)) {
 		ret = *((struct wmab_ret *) obj->buffer.pointer);
 	} else {
+		kfree(out.pointer);
 		return AE_ERROR;
 	}
 
@@ -607,15 +609,24 @@ static acpi_status AMW0_set_capabilities(void)
 	args.ebx = 2 << 8;
 	args.ebx |= ACER_AMW0_BLUETOOTH_MASK;
 
+	/*
+	 * It's ok to use existing buffer for next wmab_execute call.
+	 * But we need to kfree(out.pointer) if next wmab_execute call
+	 * returns AE_BUFFER_OVERFLOW.
+	 */
 	status = wmab_execute(&args, &out);
-	if (ACPI_FAILURE(status))
+	if (ACPI_FAILURE(status)) {
+		if (status == AE_BUFFER_OVERFLOW)
+			kfree(out.pointer);
 		return status;
+	}
 
 	obj = (union acpi_object *) out.pointer;
 	if (obj && obj->type == ACPI_TYPE_BUFFER
 	&& obj->buffer.length == sizeof(struct wmab_ret)) {
 		ret = *((struct wmab_ret *) obj->buffer.pointer);
 	} else {
+		kfree(out.pointer);
 		return AE_ERROR;
 	}
 
-- 
1.5.4.3



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